Dr. Dobb's Python-URL! - weekly Python news and links (Jun 26)
QOTW: In short, it's never what you think it is ;-) - timbot, probably on the subject of performance Real efficiency comes from elegant solutions, not optimized programs. Optimization is always just a few correctness-preserving transformations away. - Jonathan Sobel http://www.cs.indiana.edu/~jsobel/c455-c511.updated.txt Microsoft is (again) structuring its current marketing around platforms, and apparently Python is starting to show up in the campaigns: http://www.microsoft.com/presspass/press/2006/jun06/06-20MSRoboticsStudioPR.mspx Intel puts Python to good use in commercial program slicing: http://groups.google.com/group/comp.lang.python/browse_thread/thread/98cd59f90b169896/ Transcoding PVRs? Constructing collaborative whiteboards? Streaming multimedia in all directions? Apparently you can construct very impressive network-aware audiovisual applications *visually* with Kamaelia: http://groups.google.com/group/comp.lang.python/browse_thread/thread/36c89411fba299b6/ If you only care about advanced concurrency methods, pipeline- based methods, and componentry, well, that's in there, too, wrapped as Axon: http://groups.google.com/group/comp.lang.python/msg/7a5f189e886d9fc0 Discussion about the new Python icons might inspire a reader to try them: http://groups.google.com/group/comp.lang.python/browse_thread/thread/204f2792a882648d/ Wow: PyPy is up to 0.9.0: http://groups.google.com/group/comp.lang.python.announce/msg/6fa325e6c0cdd526 Life becomes more sophisticated than ever before: http://golly.sourceforge.net/ Timbot illustrates how an experienced file-comparer thinks about performance hacks (and Windows): http://groups.google.com/group/comp.lang.python/msg/15d45c2b268fa410 ... and how much deeper one can analyze recursion and numerics than merely the tastes great! less filling! level: http://groups.google.com/group/comp.lang.python/msg/e67403fcaa06c022 http://groups.google.com/group/comp.lang.python/msg/4451e63833a0c1c1 Everything Python-related you want is probably one or two clicks away in these pages: Python.org's Python Language Website is the traditional center of Pythonia http://www.python.org Notice especially the master FAQ http://www.python.org/doc/FAQ.html PythonWare complements the digest you're reading with the marvelous daily python url http://www.pythonware.com/daily Mygale is a news-gathering webcrawler that specializes in (new) World-Wide Web articles related to Python. http://www.awaretek.com/nowak/mygale.html While cosmetically similar, Mygale and the Daily Python-URL are utterly different in their technologies and generally in their results. For far, FAR more Python reading than any one mind should absorb, much of it quite interesting, several pages index much of the universe of Pybloggers. http://lowlife.jp/cgi-bin/moin.cgi/PythonProgrammersWeblog http://www.planetpython.org/ http://mechanicalcat.net/pyblagg.html comp.lang.python.announce announces new Python software. Be sure to scan this newsgroup weekly. http://groups.google.com/groups?oi=djqas_ugroup=comp.lang.python.announce Python411 indexes podcasts ... to help people learn Python ... Updates appear more-than-weekly: http://www.awaretek.com/python/index.html Steve Bethard, Tim Lesher, and Tony Meyer continue the marvelous tradition early borne by Andrew Kuchling, Michael Hudson and Brett Cannon of intelligently summarizing action on the python-dev mailing list once every other week. http://www.python.org/dev/summary/ The Python Package Index catalogues packages. http://www.python.org/pypi/ The somewhat older Vaults of Parnassus ambitiously collects references to all sorts of Python resources. http://www.vex.net/~x/parnassus/ Much of Python's real work takes place on Special-Interest Group mailing lists http://www.python.org/sigs/ Python Success Stories--from air-traffic control to on-line match-making--can inspire you or decision-makers to whom you're subject with a vision of what the language makes practical. http://www.pythonology.com/success The Python Software Foundation (PSF) has replaced the Python Consortium as an independent nexus of activity. It has official responsibility for Python's development and maintenance. http://www.python.org/psf/ Among the ways you can support PSF is with a donation. http://www.python.org/psf/donate.html Kurt B. Kaiser publishes a weekly report on faults and patches. http://www.google.com/groups?as_usubject=weekly%20python%20patch Although unmaintained
Re: What is Expressiveness in a Computer Language
On Sun, 25 Jun 2006 20:11:22 +0200, Anton van Straaten [EMAIL PROTECTED] wrote: [EMAIL PROTECTED] wrote: In this context, the term latently-typed language refers to the language that a programmer experiences, not to the subset of that language which is all that we're typically able to formally define. That language is not a subset, if at all, it's the other way round, but I'd say they are rather incomparable. That is, they are different languages. The subset characterization is not important for what I'm saying. The fact that they are different languages is what's important. If you agree about that, then you can at least understand which language I'm referring to when I say latently-typed language. Besides, many dynamically-typed languages have no formal models, in which case the untyped formal model I've referred to is just a speculative construct. The language I'm referring to with latently-typed language is the language that programmers are familiar with, and work with. That is starting to get a bit too mystical for my tastes. I have to agree. \sarcasm One step further, and somebody starts calling C a latently memory-safe language, because a real programmer knows that his code is in a safe subset... And where he is wrong, dynamic memory page protection checks will guide him. That's a pretty apt comparison, and it probably explains how it is that the software we all use, which relies so heavily on C, works as well as it does. But the comparison critiques the practice of operating without static guarantees, it's not a critique of the terminology. Anton Actually I have never developed a C/C++ program without a bounds checker the last 15 years. It checks all memory references and on program shutdown checks for memory leaks. What is it about you guys that make you blind to these fact's. Allocation problem's haven't really bugged me at all since forever. Now debugging fluky templates on the other hands.. But then debugging Lisp macro's isn't much better. -- Using Opera's revolutionary e-mail client: http://www.opera.com/mail/ -- http://mail.python.org/mailman/listinfo/python-list
list problem 4 newbie
I can't figure out why my code is not working. I thought I had the list
copied correctly:
Here is my code:
a=[[u'HF', []], [u')F', [u'75']], [u'RE', []], [u'C', []]]
b=a[:]
for index in reversed(range(0,len(a)-1)):
if '75' in b[index][1]:
b[index][1].remove('75')
b[index][1].append('99')
print a,'\n',b
but when it finishes, I get
[[u'HF', []], [u')F', ['99']], [u'RE', []], [u'C', []]]
[[u'HF', []], [u')F', ['99']], [u'RE', []], [u'C', []]]
instead of the desired:
[[u'HF', []], [u')F', ['75']], [u'RE', []], [u'C', []]]
[[u'HF', []], [u')F', ['99']], [u'RE', []], [u'C', []]]
why is this?
--
http://mail.python.org/mailman/listinfo/python-list
Re: Python sub-interpreter, security
http://aspn.activestate.com/ASPN/Cookbook/Python/Recipe/496746 [EMAIL PROTECTED] wrote: Hello, I am writing a pure-Python game engine that interprets the code of game objects within the same process with the exec statement. My main goal is to make as much power available as possible and exec seems like the best way to do that. This is my proof-of-concept code(only 18 lines and some whitespace, including the test): http://people.ucsc.edu/~jhofmann/programmables.py I showed this to the Pygame list and recieved some interest and a completely different, more sophisticated implementation: http://codereactor.net/~shang/interpret/ As-is, both versions are wide-open security holes. I think that I can patch them up if I run checks on the statements and eliminate all language features that pose risks. Then, features that are useful but not needed at their full capacity can be accessed through functions designed to be secure. Forcing a crash is not considered an exploit for this purpose(since it's a game engine - if it crashes, the user can recover and lose no data) What I'd like to know is, is it possible to meet this level of security, and if so, which features have to be eliminated? The two that I'm sure should go are module imports and self-modifying code. But in the latter case, I don't know all the ways that might be done. It seems like a very complicated problem, and if I can't solve it I might leave the whole thing unsecured. -- http://mail.python.org/mailman/listinfo/python-list
Re: What is Expressiveness in a Computer Language
Chris Smith wrote: What makes static type systems interesting is not the fact that these logical processes of reasoning exist; it is the fact that they are formalized with definite axioms and rules of inference, performed entirely on the program before execution, and designed to be entirely evaluatable in finite time bounds according to some procedure or set of rules, so that a type system may be checked and the same conclusion reached regardless of who (or what) is doing the checking. All that, and they still reach interesting conclusions about programs. There's only one issue mentioned there that needs to be negotiated w.r.t. latent types: the requirement that they are performed entirely on the program before execution. More below. If informal reasoning about types doesn't meet these criteria (and it doesn't), then it simply doesn't make sense to call it a type system (I'm using the static terminology here). It may make sense to discuss some of the ways that programmer reasoning resembles types, if indeed there are resemblances beyond just that they use the same basic rules of logic. It may even make sense to try to identify a subset of programmer reasoning that even more resembles... or perhaps even is... a type system. It still doesn't make sense to call programmer reasoning in general a type system. I'm not trying to call programmer reasoning in general a type system. I'd certainly agree that a programmer muddling his way through the development of a program, perhaps using a debugger to find all his problems empirically, may not be reasoning about anything that's sufficiently close to types to call them that. But latent means what it implies: someone who is more aware of types can do better at developing the latent types. As a starting point, let's assume we're dealing with a disciplined programmer who (following the instructions found in books such as the one at htdp.org) reasons about types, writes them in his comments, and perhaps includes assertions (or contracts in the sense of Contracts for Higher Order Functions[1]), to help check his types at runtime (and I'm talking about real type-checking, not just tag checking). When such a programmer writes a type signature as a comment associated with a function definition, in many cases he's making a claim that's provable in principle about the inputs and outputs of that function. For example, if the type in question is int - int, then the provable claim is that given an int, the function cannot return anything other than an int. Voila, assuming we can actually prove our claim, then we've satisfied the requirement in Pierce's definition of type system, i.e. proving the absence of certain program behaviors by classifying phrases according to the kinds of values they compute. The fact that the proof in question may not be automatically verified is no more relevant than the fact that so many proofs in mathematics have not been automatically verified. Besides, if the proof turns out to be wrong, we at least have an automated mechanism for finding witnesses to the error: runtime tag checks will generate an error. Such detection is not guaranteed, but again, proof does not imply automation. What I've just described walks like a type and talks like a type, or at least it appears to do so according to Pierce's definition. We can classify many terms in a given dynamically-typed program on this basis (although some languages may be better at supporting this than others). So, on what grounds do you reject this as not being an example of a type, or at the very least, something which has clear and obvious connections to formal types, as opposed to simply being arbitrary programmer reasoning? Is it the lack of a formalized type system, perhaps? I assume you recognize that it's not difficult to define such a system. Regarding errors, we haven't proved that the function in question can never be called with something other than an int, but we haven't claimed to prove that, so there's no problem there. I've already described how errors in our proofs can be detected. Another possible objection is that I'm talking about local cases, and not making any claims about extending it to an entire program (other than to observe that it can be done). But let's take this a step at a time: considered in isolation, if we can assign types to terms at the local level in a program, do you agree that these are really types, in the type theory sense? If you were to agree, then we could move on to looking at what it means to have many local situations in which we have fairly well-defined types, which may all be defined within a common type system. As an initial next step, we could simply rely on the good old universal type everywhere else in the program - it ought to be possible to make the program well-typed in that case, it would just mean that the provable properties would be
Re: Python sub-interpreter, security
faulkner wrote: http://aspn.activestate.com/ASPN/Cookbook/Python/Recipe/496746 Thanks! I was searching everywhere but couldn't find the right terms, I guess. -- http://mail.python.org/mailman/listinfo/python-list
Re: What is Expressiveness in a Computer Language
John Thingstad wrote: On Sun, 25 Jun 2006 20:11:22 +0200, Anton van Straaten [EMAIL PROTECTED] wrote: [EMAIL PROTECTED] wrote: ... \sarcasm One step further, and somebody starts calling C a latently memory-safe language, because a real programmer knows that his code is in a safe subset... And where he is wrong, dynamic memory page protection checks will guide him. That's a pretty apt comparison, and it probably explains how it is that the software we all use, which relies so heavily on C, works as well as it does. But the comparison critiques the practice of operating without static guarantees, it's not a critique of the terminology. Anton Actually I have never developed a C/C++ program without a bounds checker the last 15 years. It checks all memory references and on program shutdown checks for memory leaks. What is it about you guys that make you blind to these fact's. You misunderstand -- for the purposes of the above comparison, a bounds checker serves essentially the same purpose as dynamic memory page protection checks. The point is that it happens dynamically, i.e. at runtime, and that there's a lack of static guarantees about memory safety in C or C++. That's why, as I said, the comparison to latent vs. static typing is an apt one. Anton -- http://mail.python.org/mailman/listinfo/python-list
Re: list problem 4 newbie
Hi, if u check the id's of a and b lists and also its elements, you will obeserve that the id's of a and b have changed but id's of their elements have not changed. If you make a deep copy of the list a and then make your changes in that list, it shud work. this can be done using the copy module. hope that helps, vaibhav id(a) -1208622388 id(b) -1208622324 for el in a: ... print id(el) ... -1208622836 -1208622708 -1208622772 -1208622420 for el in b: ... print id(el) ... -1208622836 -1208622708 -1208622772 -1208622420 import copy c = copy.deepcopy(a) id(c) -1208464564 for el in c: ... print id(el) ... -1208465172 -1208464276 -1208464180 -1208463988 -- http://mail.python.org/mailman/listinfo/python-list
Re: Interactive debugging
[EMAIL PROTECTED] wrote: Hi, is there a way in python to place some sort of keyboard() type statement which stops the script and puts you back at the console? see the third example on this page: http://effbot.org/librarybook/code.htm /F -- http://mail.python.org/mailman/listinfo/python-list
Re: What is Expressiveness in a Computer Language
Joachim Durchholz wrote: Anton van Straaten schrieb: Marshall wrote: Can you be more explicit about what latent types means? Sorry, that was a huge omission. (What I get for posting at 3:30am.) The short answer is that I'm most directly referring to the types in the programmer's head. Ah, finally that terminology starts to make sense to me. I have been wondering whether there's any useful difference between latent and run-time typing. (I tend to avoid the term dynamic typing because it's overloaded with too many vague ideas.) Right, that's the reason for using a different term. Runtime and dynamic types are both usually associated with the idea of tagged values, and don't address the types of program phrases. there are usually many possible static type schemes that can be assigned to a given program. This seems to apply to latent types as well. That's what I meant, yes. Actually the set of latent types seems to be the set of possible static type schemes. Um, well, a superset of these - static type schemes tend to be slightly less expressive than what the programmer in his head. (Most type schemes cannot really express things like the range of this index variable is such-and-so, and the boundary to general assertions about the code is quite blurry anyway.) Yes, although this raises the type theory objection of how you know something is a type if you haven't formalized it. For the purposes of comparison to static types, I'm inclined to be conservative and stick to things that have close correlates in traditional static types. There's a close connection between latent types in the sense I've described, and the tagged values present at runtime. However, as type theorists will tell you, the tags used to tag values at runtime, as e.g. a number or a string or a FooBar object, are not the same thing as the sort of types which statically-typed languages have. Would that be a profound difference, or is it just that annotating a value with a full type expression would cause just too much runtime overhead? It's a profound difference. The issue is that it's not just the values that need to be annotated with types, it's also other program terms. In addition, during a single run of a program, all it can ever normally do is record the types seen on the path followed during that run, which doesn't get you to static types of terms. To figure out the static types, you really need to do static analysis. Of course, static types give an approximation of the actual types of values that flow at runtime, and if you come at it from the other direction, recording the types of values flowing through terms on multiple runs, you can get an approximation to the static type. Some systems use that kind of thing for method lookup optimization. In your terminology: So, where do tagged values fit into this? Tags help to check types at runtime, but that doesn't mean that there's a 1:1 correspondence between tags and types. Would it be possible to establish such a correspondence, would it be common consensus that such a system should be called tags anymore, or are there other, even more profound differences? There's a non 1:1 correspondence which I gave an example of in the quoted message. For 1:1 correspondence, you'd need to associate types with terms, which would need some static analysis. It might result in an interesting program browsing and debugging tool... Anton -- http://mail.python.org/mailman/listinfo/python-list
Re: Python database access
On 2006-06-26, Serge Orlov [EMAIL PROTECTED] wrote: On 25 Jun 2006 21:19:18 -0700, arvind [EMAIL PROTECTED] wrote: I am going to work on Python 2.4.3 and MSSQL database server on Windows platform. The module you're looking for is the first result if you search python mysql on google or if you search mysql on python package index http://www.python.org/pypi I think he meant Microsoft SQL Server. In which case, google searches on python mssql and python odbc should be helpful. Dave Cook -- http://mail.python.org/mailman/listinfo/python-list
Re: Python taught in schools?
In article [EMAIL PROTECTED], [EMAIL PROTECTED] (Alex Martelli) wrote: ... let's try some google searches and see the number of million hits...: But how reliable are those estimates of numbers of hits, anyway? More than once I've got a page showing something like Results 1 - 10 of about 36 hits, only to find that there were no more pages after the second one. If it could get estimates so wrong with such small numbers, how can you trust the large ones? -- http://mail.python.org/mailman/listinfo/python-list
Re: Python taught in schools?
In article [EMAIL PROTECTED], Mirco Wahab [EMAIL PROTECTED] wrote: C++ programming requires you to massively invest your thinking first into the setup of your build environment ... I don't understand why. It's easy enough to build small programs with a single g++ command. -- http://mail.python.org/mailman/listinfo/python-list
Re: Duplex communication with pipes - is possible ?
Hi !
See this shortened, simplified example. It is not working, but I don't
understand why...
# Client Process
import os, sys
from subprocess import Popen, PIPE
from time import sleep, time
from cPickle import loads, dumps
from binascii import hexlify, unhexlify
from base64 import encodestring, decodestring
from time import time
def WriteData(WStm,Data):
data=dumps(Data,1)
bdata=hexlify(data)
msg='%s#'%bdata
WStm.write(msg)
def ReadData(RStm):
tmpl=[]
while 1:
c=RStm.read(1)
if c=='#':
break
tmpl.append(c)
bdata=''.join(tmpl)
data=unhexlify(bdata)
orgdata=loads(data)
return orgdata
def SubProcessFunctions():
f=open('spp_clt.log','w')
print f,m1
while 1:
print f,m2
data=ReadData(sys.stdin)
print f,m3,[data]
if data=='quit':
print f,m4
WriteData(sys.stdout,'')
break
print f,m5
WriteData(sys.stdout,'%s'%[data])
print f,m6
if __name__=='__main__':
SubProcessFunctions()
# The Master process
from spp_clt import ReadData, WriteData
from subprocess import Popen, PIPE
import time
def MasterProcess():
print m1
p=Popen([r'c:\python24\python.exe','spp_clt.py'], \
stdin=PIPE,stdout=PIPE)
print m2
(child_stdout, child_stdin) = (p.stdout, p.stdin)
print m3
for s in range(2):
print m4
WriteData(child_stdin,s)
print m5
ReadData(child_stdout)
print m6
print m7
WriteData(child_stdin,'quit')
print m8
ReadData(child_stdout)
print m9
MasterProcess()
It is freezed, because I got deadlock. Every process got Read state,
and never get back.
What I do wrong ?
I was trying with this packet managing mode:
def WriteData(WStm,Data):
data=dumps(Data,1)
bdata=encodestring(data)
dlen=len(bdata)
msg='%12d%s'%(dlen,bdata)
if WStm==None:
print msg
else:
WStm.write(msg)
def ReadData(RStm):
dlen=int(RStm.read(12))
bdata=RStm.read(dlen)
data=decodestring(bdata)
orgdata=loads(data)
return orgdata
but it also freezed.
Why the master doesn't got the packets are sended by client ?
Thanks for your help:
dd
2006/6/21, Dara Durum [EMAIL PROTECTED]:
Hi !
Sorry, but I need multios application...
This version for text mode is working:
import subprocess
import os,sys
if 'C' in sys.argv:
#sys.stdout=open(r'c:\tpp2client.log','w')
print clt start
while 1:
head=sys.stdin.read(4)
print clt head,[head]
if head.lower()=='quit':
break
dsize=int(head)
if dsize:
data=sys.stdin.read(dsize)
print clt get data,len(data)
print clt end\n
else:
print MS
p=subprocess.Popen([r'c:\python24\python.exe','tpp2.py','C'], \
stdin=subprocess.PIPE,stdout=subprocess.PIPE)
print MSS
(child_stdout, child_stdin) = (p.stdout, p.stdin)
data=range(1000)
import cPickle
bdata=cPickle.dumps(data,1)
print len(bdata)
import binascii
hdata=binascii.hexlify(bdata)
print len(hdata)
import base64
hdata=base64.encodestring(bdata)
print len(hdata)
child_stdin.write('%04d'%len(hdata))
child_stdin.write(hdata)
child_stdin.write('quit')
output=child_stdout.readlines()
print Client's answer:\n,''*80
for s in output:
print s.strip()
print ''*80
print MEE
I will see your idea: the bittorrent...
Thanx:
dd
2006/6/20, Daniel Dittmar [EMAIL PROTECTED]:
Dara Durum wrote:
Now I trying with packet size decreasing. Are PIPE-s can handle the
binary data packets, or I need to convert them with base64 ?
In the client, you need to set the mode of sys.stdin to binary,
otherwise, you get the DOS translation of linefeeds. See
http://mail.python.org/pipermail/python-list/2000-January/020463.html
for some hints.
I assume that the stream returned by subprocess.popen are also opened in
text mode and you have to change them tobinary, see the second hint in
the link mentioned above.
Daniel
--
http://mail.python.org/mailman/listinfo/python-list
from spp_clt import ReadData, WriteData
from subprocess import Popen, PIPE
import time
def MasterProcess():
print m1
p=Popen([r'c:\python24\python.exe','spp_clt.py'], \
stdin=PIPE,stdout=PIPE)
print m2
(child_stdout, child_stdin) = (p.stdout, p.stdin)
print m3
for s in range(2):
print m4
WriteData(child_stdin,s)
print m5
ReadData(child_stdout)
print m6
print m7
WriteData(child_stdin,'quit')
print m8
ReadData(child_stdout)
print m9
MasterProcess()import os, sys
from subprocess import Popen, PIPE
from shamd5mod import HashWithSHAMD5
from custom_procthr import CustomSubProcClass
from time import sleep, time
from cPickle import loads, dumps
from binascii import hexlify, unhexlify
from base64 import encodestring, decodestring
from threading import Thread
from Queue import Queue
from time import
Re: What technologies should I use for my application manager?
MrBlueSky wrote: Hello! I've just finished working on my first Python app (a Tkinter-based program that displays the content of our application log files in graphical format). It was a great experience that's had a very positive response from my colleagues. So I'd like to try something different for my second Python application. It's a simple server that can launch and monitor the state of our program, to help our software developers. In my mind I have a vision of: * a web server * allows the user to launch our product (choosing from a set of different launch scripts) * allow user to stop a launched product * report state by retrieving data from the RDBMS against which the product runs (Oracle or SQL Server) There seem to be a lot of web server related Python libraries around, and I've no experience in web servers at all. So I'd really appreciate some advice on what Python technologies you think I should base my application on. For speed of development I would suggest looking into a framework that can do some of the heavy lifting for you. Out of those the really big names in python are Turbogears ( http://www.turbogears.org/ ), Django ( http://www.djangoproject.org/ ), and Zope ( http://www.zope.org ). (along with others that I have forgotten who shall most likely be mentioned promptly) Of them all I have the most experience with Turbogears, so that is what I will try and sell you on. By default Turbogears provides support for *either* MS SQL or Oracle. One of the differences between Turbogears and most web frameworks is that many of the bigger chunks of code for it are taken from existing projects instead of being written internally. Due to this Turbogears provides support for two database mappers: Sqlobject, which supports MS SQL; and Sqlalchemy, which supports Oracle. Of the two Sqlalchemy is much more flexible, but is also a newer project and may be harder to work with until the api finishes settling. Both projects offer full support for one of the databases you mentioned, and developmental support for the other. If you need to work with both it is possible to bring in the database integration method of your choice. Turbogears has a very flexible widget system that supports a lot of interesting code. Basic things like user input forms can be handled with widgets, but there are also prebuilt widgets for things like find-as-you-type form fields, calendar-based date pickers, tabbed displays, syntax-highlighted text, and a plotting kit (and those are just the fancy things that looked like they would be useful). There is a pretty nice validation system that can handle converting user input into appropriately typed python objects, and can automatically force a correction page if you would like it to do so. Like any other framework Turbogears has a templating system to help handle the html/css/javascript that you will be using. By default it uses Kid, which is XHTML with an additional namespace that provides support for looping, element replacement, and limited function definitions. Overall I have found it to be pretty nice to work with. That said if you want something else you can install plugins for a few different templating languages. (Currently supported are Cheetah, Stan, ZPT, HtmlPy, Clearsilver, Myghty, and Python String Templates) Obviously some of the more important parts you are looking for are integration into the system environment, logging, and possibly user authentication and scheduled tasks. By default Turbogears supports all of the access to the surrounding system that Python does. This is kind of a no-brainer, but for me at least was something of a stumbling block in coming from PHP. The logging system is based on the built-in logging package for Python. It is configured through Turbogears to allow some of the components involved to support it. You have access to pretty much all of the facilities that the Python logger provides. User authentication in Turbogears is generally handled through the Identity system. This allows you to restrict access to directories, pages, and even specific page elements (like links or forms) based on the connecting host, user account, group membership, or permissions granted. The identity system itself is pretty extensible and can probably be made to support anything you can think of as an authentication method. Scheduled tasks can be handled from inside of turbogears with the built in scheduler. This allows you to schedule tasks while working inside turbogears, which saves the headache of handling database access separately. Installing and configuring Turbogears can actually be pretty simple. The system is based around python eggs ( http://peak.telecommunity.com/DevCenter/PythonEggs/ ) which can handle installation requirements and upgrades for you. Overall I have found Turbogears to be a flexible, easy-to-use framework. It generally seems to do well at staying out of the way, and most of the extra features it adds have
Re: list problem 4 newbie
manstey wrote:
for index in reversed(range(0,len(a)-1)):
if '75' in b[index][1]:
b[index][1].remove('75')
b[index][1].append('99')
What on earth is all that messing around in the for loop intended to do? If
you want a range from len(a)-2 to 0 inclusive then just do it in range
directly (and did you really mean not to look at the last element?), if you
actually just wanted to iterate through b in reverse, then just iterate
through b in reverse:
b = copy.deepcopy(a)
for element in reversed(b):
if '75' in element[1]:
element[1].remove('75')
element[1].append('99')
--
http://mail.python.org/mailman/listinfo/python-list
Re: What is Expressiveness in a Computer Language
Rob Thorpe [EMAIL PROTECTED] writes: I think statements like this are confusing, because there are different interpretations of what a value is. But I mean the value as the semantics of the program itself sees it. Which mostly means the datum in memory. I don't agree with that. Generally, a language specifies a virtual machine and doesn't need to concern itself with things like memory at all. Although langauges like C tries to, look at all the undefined behavior you get when you make assumptions about memory layout etc. Memory representation is just an artifact of a particular implementation of the language for a particular architecture. -k -- If I haven't seen further, it is by standing in the footprints of giants -- http://mail.python.org/mailman/listinfo/python-list
Re: Pygame.draw challenge is over!
Richard Jones wrote: spiffy wrote: Congrats to Seth Yastrov for 'gravity.py' ... THE ONLY ONE THAT WORKED! I did test that they all worked on my machine before putting them online... What issues are you having? What OS? The only issue I found is that goop dies with IndexError: list index out of range if you move to to the top right corner. -- http://mail.python.org/mailman/listinfo/python-list
Re: What is Expressiveness in a Computer Language
Anton van Straaten [EMAIL PROTECTED] wrote: I'm not trying to call programmer reasoning in general a type system. I'd certainly agree that a programmer muddling his way through the development of a program, perhaps using a debugger to find all his problems empirically, may not be reasoning about anything that's sufficiently close to types to call them that. Let me be clear, then. I am far less agreeable than you that this couldn't be called a type system. One of my goals here is to try to understand, if we are going to work out what can and can't be called a type system in human thought, how we can possible draw a boundary between kinds of logic and say that one of them is a type system while the other is not. I haven't seen much of a convincing way to do it. The only things that I can see rejecting out of hand are the empirical things; confidence gained through testing or observation of the program in a debugger. Everything else seems to qualify, and that's the problem. So let's go ahead and agree about everything up until... [...] As an initial next step, we could simply rely on the good old universal type everywhere else in the program - it ought to be possible to make the program well-typed in that case, it would just mean that the provable properties would be nowhere near as pervasive as with a traditional statically-typed program. It would, in fact, mean that interesting provable properties would only be provable if data can't flow outside of those individual small bits where the programmer reasoned with types. Of course that's not true, or the programmer wouldn't have written the rest of the program in the first place. If we define the universal type as a variant type (basically, tagged or something like it, so that the type can be tested at runtime) then certain statements become provable, of the form either X or some error condition is raised because a value is inappropriate. That is indeed a very useful property; but wouldn't it be easier to simply prove it by appealing to the language semantics that say that if not X, the operation raises an exception, or to the existence of assertions within the function that verify X, or some other such thing (which must exist, or the statement wouldn't be true)? But the point is we would now have put our types into a formal context. Yes, but somewhat vacuously so... The point about inherent informality is just that if you fully formalize a static type system for a dynamic language, such that entire programs can be statically typed, you're likely to end up with a static type system with the same disadvantages that the dynamic language was trying to avoid. Okay, so you've forced the admission that you have a static type system that isn't checked and doesn't prove anything interesting. If you extended the static type system to cover the whole program, then you'd have a statically typed language that lacks an implementation of the type checker. I don't see what we lose in generality by saying that the language lacks a static type system, since it isn't checked, and doesn't prove anything anyway. The remaining statement is that the programmer may use static types to reason about the code. But, once again, the problem here is that I don't see any meaning to that. It would basically mean the same thing as that the programmer may use logic to reason about code. That isn't particularly surprising to me. I suppose this is why I'm searching for what is meant by saying that programmers reason about types, and am having that conversation in several places throughout this thread... because otherwise, it doesn't make sense to point out that programmers reason with types. Well, I'm trying to use the term latent type, as a way to avoid the ambiguity of type alone, to distinguish it from static type, and to get away from the obvious problems with dynamic type. I replied to your saying something to Marshall about the type systems (in the static sense) of dynamically-typed languages. That's what my comments are addressing. If you somehow meant something other than the static sense, then I suppose this was all a big misunderstanding. But I'm much less interested in the term itself than in the issues surrounding dealing with real types in dynamically-checked programs - if someone had a better term, I'd be all in favor of it. I will only repeat again that in static type systems, the type becomes a degenerate concept when it is removed from the type system. It is only the type system that makes something a type. Therefore, if you want real types, then my first intuition is that you should avoid looking in the static types of programming languages. At best, they happen to coincide frequently with real types, but that's only a pragmatic issue if it means anything at all. So when well-typed program fragments are considered as part of a larger untyped program, you're
Re: Kamaelia 0.4.0 RELEASED - Faster! More Tools! More Examples! More Docs! ; -)
This allows somethings to run eg AxonVisualiser.py --navelgaze but I'm not sure if the results are really unaffected by not having a real yielder. The diagram appears, but doesn't seem to settle down. I don't think the AxonVisualiser would be particularly affected by this - any wobbling you'll see there is probably more down to the simple physics model the visualiser uses not having sufficient dampening for the layout you see. (The physics model was apparently originally written by Matt for a lava lamp simulator, but has turned out to be incredibly useful as a simple layout tool :-) A little bit of manual assistance to spread things out can sometimes help it settle down though :) Michael's right: the wobble is due to the low level of dampening in the physics model and its discrete time step nature. Brief, non-methodical(!) experiments with increased dampening do lead to a more stable visualisation, but particles start to become 'sticky' and not always move when it would be helpful for them to do so! The physics code is not the fastest on the planet, so the number of simulation cycles per second is quite low - therefore to enable the particles to move quickly enough, the forces act quite strongly and the dampening is quite low. You therefore occasionally see a slight wobbling effect where a 'component' particle is being pulled and pushed quite strongly by its inbox and outbox particles in many different directions at once. Matt -- | Matt Hammond | Research Engineer, Tech. Group, BBC, Kingswood Warren, Tadworth, Surrey, UK | http://kamaelia.sf.net/ | http://www.bbc.co.uk/rd/ -- http://mail.python.org/mailman/listinfo/python-list
Re: Python taught in schools?
Lawrence D'Oliveiro wrote: In article [EMAIL PROTECTED], [EMAIL PROTECTED] (Alex Martelli) wrote: ... let's try some google searches and see the number of million hits...: But how reliable are those estimates of numbers of hits, anyway? More than once I've got a page showing something like Results 1 - 10 of about 36 hits, only to find that there were no more pages after the second one. If it could get estimates so wrong with such small numbers, how can you trust the large ones? If you read what it says at the bottom of the last page of results (this example from a claimed 90 hits, but only 27 visible): In order to show you the most relevant results, we have omitted some entries very similar to the 27 already displayed. If you like, you can repeat the search with the omitted results included. Google's hit count includes all the pages which by default it filters out. In particular it only returns you two pages from each site in the initial results (grouped together and with the second one indented). If you repeat the search with filtering turned off then you should find that a small count of hits is pretty accurate). -- http://mail.python.org/mailman/listinfo/python-list
Re: Interactive debugging
[EMAIL PROTECTED] wrote: Hi, is there a way in python to place some sort of keyboard() type statement which stops the script and puts you back at the console? I'm looking for something like in matlab, where you place a keyboard() command (I think), then you're in debug mode in the console, and you type continue to re-enter the script where you left off. While you're in the debugger/console you're at the scope where the keyboard() call was and you can manipulate variables, etc. Is there something like this in python? I've been using winpdb, which is great, but sometimes I need more interactivity. Is this what pdb is about? Use import pdb pdb.set_trace() The line where the set_trace() is invoked puts you back in the interpreter. Diez -- http://mail.python.org/mailman/listinfo/python-list
Re: Mix-In Class Methods At Run-Time
[EMAIL PROTECTED] wrote:
(snip)
Two additional questions though: 1) is there a way for a function to
get a reference to its caller automatically (as in, without the caller
having to pass it in)?
It's possible with sys._getframe() and a decorator - but consider it a
hack.
and 2) what's the reason to use newstyle classes
versus the old?
All this is explained on python.org (there's a menu entry for this in
the documentation menu). AFAICT, newstyle classes can do whatever
oldstyle classes did, *and much more* (descriptors and usable
metaclasses) - and they are somewhat faster too. So - compatibility with
older Python versions ( 2.2 IIRC) set aside -, there's just no reason
to use oldstyle classes.
In order to create the dynamic class NewClass in the
code above I called type() but that requires at least one new style
class as a base. Thus, I had to have at least one of my animals inherit
from object and this seemed a nuisance since
OMG, eight more keystrokes - talk about a nuisance...
I don't at this point
know what the benefit of newstyle classes is.
See it the other way round : the *only* benefit of oldstyle classes is
compatibility with pre-2.2 Python versions.
--
bruno desthuilliers
python -c print '@'.join(['.'.join([w[::-1] for w in p.split('.')]) for
p in '[EMAIL PROTECTED]'.split('@')])
--
http://mail.python.org/mailman/listinfo/python-list
Re: error with string (beginner)
Jason wrote:
I believe what you are trying to do is something like the following.
[code]
def isIntLike(x):
try:int(x)
except: return False
*Never* ever use a bare except clause. *Always* specify wich exceptions
you are expecting. (NB : here, TypeError and ValueError).
(NB : of course, like for all and any do's-and-don't rules, there are
actually a very few cases where using a bare except may be ok.)
else: return True
something = raw_input(Enter something and I will tell you the type: )
if isIntLike(something): print I am an int
Nope. At this stage, 'something' is *not* an int - it's a string that
can be turned into an int.
elif isinstance(something, type('')): print I am a string
You don't need the type('') stuff - use isinstance(something,
basestring) instead.
else: print I am an impostor!
[/code]
(snip)
--
bruno desthuilliers
python -c print '@'.join(['.'.join([w[::-1] for w in p.split('.')]) for
p in '[EMAIL PROTECTED]'.split('@')])
--
http://mail.python.org/mailman/listinfo/python-list
style question
Is it better to do: message = This is line1. This is line2 This is line3\n or message = This is line1.\n message = message + This is line2\n message = message + This is line3\n Since the first method does not follow python's clean and easy looking indentation structure but the second just looks crude and ugly anyway. If I indent the first version so the text is lined up to match code indentation then this comes out in the input and isn't aligned there. -- http://mail.python.org/mailman/listinfo/python-list
Re: Python question
Harry wrote:
Hi All,
(snip)
I have the following object which is like a list of tuples
row= [('name', 'x1'), ('min', 15.449041129349528), ('max',
991.6337818245629), ('range', 976.18474069521335), ('mean',
496.82174193958127), ('stddev', 304.78275004920454), ('variance',
92892.524727555894), ('mode', '46.5818482111'), ('unique_count', '99'),
('count', 99.0), ('count_missing', 0.0), ('sum_weight', 99.0)]
FWIW, it *is* a list of tuples.
What command
ot What's a 'command' ? /ot
do I use to get the value corresponding to 'min'?
(see below...)
This object seems to be non-indexable
It is - just like any other list. Try :
print row[0]
print row[1]
# etc...
Now if you want keyword access, try this:
print dict(row)['min']
--
bruno desthuilliers
python -c print '@'.join(['.'.join([w[::-1] for w in p.split('.')]) for
p in '[EMAIL PROTECTED]'.split('@')])
--
http://mail.python.org/mailman/listinfo/python-list
Re: style question
Hari Sekhon wrote: Is it better to do: message = This is line1. This is line2 This is line3\n or message = This is line1.\n message = message + This is line2\n message = message + This is line3\n Is there any reason you can't do it in one line? message = This is line1.\nThis is line2.\nThis is line3.\n -- http://mail.python.org/mailman/listinfo/python-list
Re: style question
MTD wrote: Hari Sekhon wrote: Is it better to do: message = """This is line1. This is line2 This is line3\n""" or message = "This is line1.\n message = message + "This is line2\n" message = message + "This is line3\n" Is there any reason you can't do it in one line? message = "This is line1.\nThis is line2.\nThis is line3.\n" this would also be ugly though, a huge lone line for the paragraph I want to output, which would wrap around and break the visual indentation. otherwise I could do it in one line. but if I was going to do that and it was going to be so long, I'd just use """...""" -- http://mail.python.org/mailman/listinfo/python-list
Re: Mix-In Class Methods At Run-Time
I can't give much answers, I am not that expert yet. Bruno Desthuilliers: newstyle classes can do whatever oldstyle classes did, *and much more* (descriptors and usable metaclasses) - and they are somewhat faster too. In the past I have done few tests, and it seemed that new style classes are a bit slower (but the difference doesn't make much difference). Maybe for Py2.5 the situation will be different. Bye, bearophile -- http://mail.python.org/mailman/listinfo/python-list
Re: style question
Hari Sekhon wrote: Is it better to do: message = This is line1. This is line2 This is line3\n or message = This is line1.\n message = message + This is line2\n message = message + This is line3\n Since the first method does not follow python's clean and easy looking indentation structure but the second just looks crude and ugly anyway. If I indent the first version so the text is lined up to match code indentation then this comes out in the input and isn't aligned there. How about message = (This is line1. This is line2 This is line3\n) The brackets mean that the lines are automatically treated as continuous, without the need for the ugly '\' continuation character. The opening/closing quotes on each line mean that the strings are contatenated into one long string. Frank Millman -- http://mail.python.org/mailman/listinfo/python-list
Re: style question
Frank Millman wrote: How about message = (This is line1. This is line2 This is line3\n) The brackets mean that the lines are automatically treated as continuous, without the need for the ugly '\' continuation character. The opening/closing quotes on each line mean that the strings are contatenated into one long string. Frank Millman Don't know what happened there - Google seems to have messed up my indentation. My intention was that each of the three leading quote marks line up vertically, but when I read it back via Google Groups, the second two lines were pushed over to the right. Frank -- http://mail.python.org/mailman/listinfo/python-list
Re: style question
Hari Sekhon wrote: Is it better to do: message = This is line1. This is line2 This is line3\n or message = This is line1.\n message = message + This is line2\n message = message + This is line3\n Since the first method does not follow python's clean and easy looking indentation structure but the second just looks crude and ugly anyway. If I indent the first version so the text is lined up to match code indentation then this comes out in the input and isn't aligned there. Hi, msgs = ['This is line1.','This is line2.','This is line3.'] message = '\n'.join(msgs) Regards, Laurent. -- http://mail.python.org/mailman/listinfo/python-list
Re: style question
Frank Millman wrote: How about message = (This is line1. This is line2 This is line3\n) The brackets mean that the lines are automatically treated as continuous, without the need for the ugly '\' continuation character. The opening/closing quotes on each line mean that the strings are contatenated into one long string. Don't know what happened there - Google seems to have messed up my indentation. My intention was that each of the three leading quote marks line up vertically, but when I read it back via Google Groups, the second two lines were pushed over to the right. assuming fixed-pitch fonts isn't very Pythonic, though; to get reliable indentation no matter what font you're using, you can write: message = ( This is line1. This is line2 This is line3\n) whether this is better than depends on the situation. /F -- http://mail.python.org/mailman/listinfo/python-list
Re: What is Expressiveness in a Computer Language
Chris Smith [EMAIL PROTECTED] writes: I've since abandoned any attempt to be picky about use of the word type. That was a mistake on my part. I still think it's legitimate to object to statements of the form statically typed languages X, but dynamically typed languages Y, in which it is implied that Y is distinct from X. When I used the word type above, I was adopting the working definition of a type from the dynamic sense. Umm...what *is* the definition of a dynamic type? In this thread it's been argued from tags and memory representation to (almost?) arbitrary predicates. That is, I'm considering whether statically typed languages may be considered to also have dynamic types, and it's pretty clear to me that they do. Well, if you equate tags with dynamic types: data Universal = Str String | Int Integer | Real Double | List [Universal] ... A pattern match failure can then be seen as a dynamic type error. Another question is how to treat a system (and I think C++'s RTTI qualifies, and probably related languages like Java) where static type information is available at runtime. Does this fit with the term dynamic typing with typing in the same sense as static typing? -k -- If I haven't seen further, it is by standing in the footprints of giants -- http://mail.python.org/mailman/listinfo/python-list
Re: style question
Fredrik Lundh wrote: Frank Millman wrote: How about message = (This is line1. This is line2 This is line3\n) The brackets mean that the lines are automatically treated as continuous, without the need for the ugly '\' continuation character. The opening/closing quotes on each line mean that the strings are contatenated into one long string. Don't know what happened there - Google seems to have messed up my indentation. My intention was that each of the three leading quote marks line up vertically, but when I read it back via Google Groups, the second two lines were pushed over to the right. assuming fixed-pitch fonts isn't very Pythonic, though; to get reliable indentation no matter what font you're using, you can write: message = ( This is line1. This is line2 This is line3\n) whether this is better than depends on the situation. /F Obvious, now that you mention it. Thank you. Frank -- http://mail.python.org/mailman/listinfo/python-list
Re: Python taught in schools?
Thus spoke Lawrence D'Oliveiro (on 2006-06-26 09:21): In article [EMAIL PROTECTED], Mirco Wahab [EMAIL PROTECTED] wrote: C++ programming requires you to massively invest your thinking first into the setup of your build environment ... I don't understand why. It's easy enough to build small programs with a single g++ command. Think about beeing a young guy with a windows pc at home. To make sense of your 45 min C++ class, you need to practice the stuff at home for sure, I'd guess. Now go ahead! What would you do? Download The C++ from the Internet, click on setup and start? Right ;-) Regards Mirco -- http://mail.python.org/mailman/listinfo/python-list
Re: style question
Hari Sekhon wrote: Since the first method does not follow python's clean and easy looking indentation structure but the second just looks crude and ugly anyway. If you want indented and pretty is important to you: from textwrap import dedent as D message = D(\ This is line1. This is line2 This is line3 ) message 'This is line1.\nThis is line2\nThis is line3\n' Usually though I would just make sure that long strings are declared at module level and not indent them. The backslash after the opening quotes stops the first line being indented differently: message = \ This is line1. This is line2 This is line3 -- http://mail.python.org/mailman/listinfo/python-list
Re: What is Expressiveness in a Computer Language
Chris Smith [EMAIL PROTECTED] writes:
Joachim Durchholz [EMAIL PROTECTED] wrote:
Assume a language that
a) defines that a program is type-correct iff HM inference establishes
that there are no type errors
b) compiles a type-incorrect program anyway, with an establishes
rigorous semantics for such programs (e.g. by throwing exceptions as
appropriate).
So the compiler now attempts to prove theorems about the program, but
once it has done so it uses the results merely to optimize its runtime
behavior and then throws the results away.
Hmm... here's my compiler front end (for Haskell or other languages
that ..er.. define 'undefined'):
while(type error) {
replace an incorrectly typed function with 'undefined'
}
Wouldn't the resulting program still be statically typed?
In practice I prefer to (and do) define troublesome functions as
'undefined' manually during development.
-k
--
If I haven't seen further, it is by standing in the footprints of giants
--
http://mail.python.org/mailman/listinfo/python-list
Re: pypy-0.9.0: stackless, new extension compiler
Hi all! Michael Hudson wrote: The PyPy development team has been busy working and we've now packaged our latest improvements, completed work and new experiments as version 0.9.0, our fourth public release. Unfortunately the download links for the release tarballs did not work until very recently. They are now working though. You can download the 0.9 release of PyPy under: http://codespeak.net/download/pypy/pypy-0.9.0.tar.bz2 http://codespeak.net/download/pypy/pypy-0.9.0.tar.gz http://codespeak.net/download/pypy/pypy-0.9.0.zip For detailed notes about how to get started into the world of PyPy see here: http://codespeak.net/pypy/dist/pypy/doc/getting-started.html Sorry for the fuss and cheers, Carl Friedrich Bolz -- http://mail.python.org/mailman/listinfo/python-list
Re: What is Expressiveness in a Computer Language
Anton van Straaten [EMAIL PROTECTED] writes: But a program as seen by the programmer has types: the programmer performs (static) type inference when reasoning about the program, and debugs those inferences when debugging the program, finally ending up with a program which has a perfectly good type scheme. I'd be tempted to go further, and say that the programmer performs (informally, incompletely, and probably incorrectly ) a proof of correctness, and that type correctness is just a part of general correctness. -k -- If I haven't seen further, it is by standing in the footprints of giants -- http://mail.python.org/mailman/listinfo/python-list
Re: What is Expressiveness in a Computer Language
Gabriel Dos Reis wrote: [EMAIL PROTECTED] writes: | think that it is too relevant for the discussion at hand. Moreover, | Harper talks about a relative concept of C-safety. Then, I believe you missed the entire point. I think the part of my reply you snipped addressed it well enough. Anyway, I can't believe that we actually need to argue about the fact that - for any *useful* and *practical* notion of safety - C is *not* a safe language. I refrain from continuing the discussion along this line, because *that* is *really* silly. - Andreas -- http://mail.python.org/mailman/listinfo/python-list
About python 2.5 and its try statement.
I can't remember the proposal number, but many of you reading will have probably read the features that will be added to python 2.5. The actual part I wanted to talk about was the finally part of try. Isn't it totally defeating a compiler's job by executing the finally part even if there is an error in the previous statements? Or have I understood something wrong? -- http://mail.python.org/mailman/listinfo/python-list
Re: Python database access
arvind wrote: Hi all, I am going to work on Python 2.4.3 and MSSQL database server on Windows platform. But I don't know how to make the connectivity or rather which module to import. I searched for the modules in the Python library, but I couldn't find which module to go for. Please help me out! I think there are a few recipes for mssql in the activestate python cookbook, or at least for odbc. -- http://mail.python.org/mailman/listinfo/python-list
Re: About python 2.5 and its try statement.
Hi, defcon8 wrote: I can't remember the proposal number, but many of you reading will have probably read the features that will be added to python 2.5. The actual part I wanted to talk about was the finally part of try. Isn't it totally defeating a compiler's job by executing the finally part even if there is an error in the previous statements? Or have I understood something wrong? try ... finally already exists in current python; what's new is that it can be combined in 1 statement with try ... except ... finally. No, this is not defeating a compilers job. It's very useful. It defines an amount of cleanup that needs to happen no matter what, exception or no exception. Example: closing an open file. You'll want to close the file, whether after you done the job you intended to do, or after an exception occurred while doing something. So you put 'f.close()' in your finally - suite. Another example of a useful 'finally' is logging function-exit -- not the actual 'return' statement, but just a log-statement recording function-exit. (Putting a 'return' statement in a 'finally' suite is totally defeating the point of exceptions that you want thrown to the caller, yes. So don't put your 'return' statement there.) Clearer? Cheers, --Tim -- http://mail.python.org/mailman/listinfo/python-list
RE: SWIG problems with gcc and Cygwin?
No response yet. The SWIG test works fine in Linux no problems.
However, I still have the problem in Cygwin.
Also, not sure if related but I do have a win32 Python 2.4.3 and
Cygwin Python 2.4.1. Not sure if there are any conflicts. Any advice
in making these two co-exist?
The only C/C++ compiler I have presently is Cygwin gcc.
Thanks in advance:
Michael Yanowitz
-Original Message-
From: [EMAIL PROTECTED]
[mailto:[EMAIL PROTECTED] Behalf
Of Michael Yanowitz
Sent: Tuesday, June 20, 2006 3:39 PM
To: python-list@python.org
Subject: SWIG problems with gcc and Cygwin?
Hello:
I am just trying out SWIG, but quickly ran into problems.
Using Cygwin gcc, I tried the following:
1) Created example.c (as given on http://www.swig.org/tutorial.html )
/* File : example.c */
#include time.h
double My_variable = 3.0;
int fact(int n) {
if (n = 1) return 1;
else return n*fact(n-1);
}
int my_mod(int x, int y) {
return (x%y);
}
char *get_time()
{
time_t ltime;
time(ltime);
return ctime(ltime);
}
2) Create interface file, example.i
/* example.i */
%module example
%{
/* Put header files here or function declarations like below */
extern double My_variable;
extern int fact(int n);
extern int my_mod(int x, int y);
extern char *get_time();
%}
extern double My_variable;
extern int fact(int n);
extern int my_mod(int x, int y);
extern char *get_time();
3)ran in cygwin: swig -i python example.i
4)Attempted to run on cygwin: ld -shared example.o example_wrap.o -o
_example.so
But got back many errors:
example.o:example.c:(.text+0x55): undefined reference to `time'
example.o:example.c:(.text+0x60): undefined reference to `ctime'
example_wrap.o:example_wrap.c:(.text+0x9c): undefined reference to `strlen'
example_wrap.o:example_wrap.c:(.text+0x12c): undefined reference to `strlen'
example_wrap.o:example_wrap.c:(.text+0x1dd): undefined reference to `strcmp'
example_wrap.o:example_wrap.c:(.text+0x494): undefined reference to `strcmp'
example_wrap.o:example_wrap.c:(.text+0x748): undefined reference to `strlen'
example_wrap.o:example_wrap.c:(.text+0x779): undefined reference to `strcpy'
example_wrap.o:example_wrap.c:(.text+0x7a5): undefined reference to `strcmp'
example_wrap.o:example_wrap.c:(.text+0x805): undefined reference to `strlen'
example_wrap.o:example_wrap.c:(.text+0x877): undefined reference to
`strncpy'
example_wrap.o:example_wrap.c:(.text+0x8ab): undefined reference to `strcmp'
example_wrap.o:example_wrap.c:(.text+0x8c9): undefined reference to `memset'
example_wrap.o:example_wrap.c:(.text+0x948): undefined reference to `fputs'
example_wrap.o:example_wrap.c:(.text+0x95d): undefined reference to `fputs'
example_wrap.o:example_wrap.c:(.text+0x970): undefined reference to `fputs'
example_wrap.o:example_wrap.c:(.text+0x9db): undefined reference to
`PyString_Fr
omFormat'
example_wrap.o:example_wrap.c:(.text+0xa3a): undefined reference to
`PyString_Fr
omString'
example_wrap.o:example_wrap.c:(.text+0xa68): undefined reference to
`PyLong_From
VoidPtr'
example_wrap.o:example_wrap.c:(.text+0xa83): undefined reference to
`PyTuple_New
etc...
Any idea what I am doing wrong or omitted?
Of course when I then try to go into python and
import example, I get:
import example
Traceback (most recent call last):
File stdin, line 1, in ?
File example.py, line 5, in ?
import _example
ImportError: No module named _example
Thanks in advance:
Michael Yanowitz
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Help with conversion VB script to Python : COM objects
Hi, I need to re-write a VB script into Python (because I really don't like VB). The VB script is used to create a Windows COM object. (I am more of Unix guy, so COM objects are a little bit alien for me). At a certain point in the VB script, I have the following line: objPolTypes = objPmad.Cvar(objPmad.GetPolicyTypeList) Does anybody what the equivalent in Python would be? I tried: objPolTypes = objPmad.Cvar(objPmad.GetPolicyTypeList() ) but then I get the following error: Traceback (most recent call last): File C:\Python24\MyProgs\FodFin\test.py, line 11, in ? objPolTypes = objPmad.cvar(objPmad.GetPolicyTypeList() ) File COMObject PMAD.OvPmdPolicyManager, line 2, in cvar pywintypes.com_error: (-2147352571, 'Type mismatch.', None, 1) I also tried : objPolTypes = objPmad.GetPolicyTypeList() this works but I end of with a list of COM object and have no clue how to query/use them or what methods are defined for those type of objects. Any help really appreciated. With kind regards, KRis -- http://mail.python.org/mailman/listinfo/python-list
Re: About python 2.5 and its try statement.
defcon8 wrote:
I can't remember the proposal number,
http://docs.python.org/dev/whatsnew/pep-341.html
but many of you reading will have
probably read the features that will be added to python 2.5. The actual
part I wanted to talk about was the finally part of try.
It has been here from the start (well, IIRC, it's since at least 1.5.2)
- the only limitation was that you couldn't use both 'except' and
'finally' in the same statement, so you had to wrap'em when needed.
Isn't it
totally defeating a compiler's job by executing the finally part even
if there is an error in the previous statements?
I don't see how this relates to the compiler. But anyway, the whole
point of the 'finally' clause is (and has ever been) to *ensure* this
block gets executed *whatever* happened. FWIW, the canonical use case is
resource aquisition/release.
Or have I understood
something wrong?
Seems so - unless it's me misunderstading your question.
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automatic debugger?
hi is there something like an automatic debugger module available in python? Say if i enable this auto debugger, it is able to run thru the whole python program, print variable values at each point, or print calls to functions..etc...just like the pdb module, but now it's automatic. thanks -- http://mail.python.org/mailman/listinfo/python-list
Re: About python 2.5 and its try statement.
defcon8 wrote: I can't remember the proposal number, but many of you reading will have probably read the features that will be added to python 2.5. The actual part I wanted to talk about was the finally part of try. Isn't it totally defeating a compiler's job by executing the finally part even if there is an error in the previous statements? Or have I understood something wrong? sounds like you're confusing compilation and execution, and compilation errors (syntax errors) with runtime errors (exceptions). try-finally is a runtime thing, not a compile time thing. /F -- http://mail.python.org/mailman/listinfo/python-list
Re: SWIG problems with gcc and Cygwin?
Michael Yanowitz wrote: Also, not sure if related but I do have a win32 Python 2.4.3 and Cygwin Python 2.4.1. Not sure if there are any conflicts. Any advice in making these two co-exist? SWIG will work with the windows and cygwin python, just make sure you don't mix the various platforms. - Install two separate versions of swig one for windows (binary) and compile one in cygwin, - Pay attention to the path and make sure that you invoke the correct swig and python Istvan. -- http://mail.python.org/mailman/listinfo/python-list
Re: String negative indices?
On 2006-06-23, Filip Wasilewski [EMAIL PROTECTED] wrote: [EMAIL PROTECTED] wrote: Logically, I should be able to enter x[-2:-0] to get the last and next to last characters. However, since Python doesn't distinguish between positive and negative zero, this doesn't work. Instead, I have to enter x[-2:]. Hooray! Logically there is no such thing as positive or negative zero, or did I miss something in the primary? PS. x[len(x)-2 : len(x)-0] This seems to defeat the purpose of allowing negative indexes. My understanding was that negative indexes were introduced to avoid things like seq[len(seq) - i] -- Antoon Pardon -- http://mail.python.org/mailman/listinfo/python-list
Re: automatic debugger?
[EMAIL PROTECTED] writes: is there something like an automatic debugger module available in python? Say if i enable this auto debugger, it is able to run thru the whole python program, print variable values at each point, or print calls to functions..etc...just like the pdb module, but now it's automatic. Dunno about Python but www.askigor.com automatically finds the bugs in C programs. It's amazing. -- http://mail.python.org/mailman/listinfo/python-list
Re: Mix-In Class Methods At Run-Time
Bruno Desthuilliers wrote:
[EMAIL PROTECTED] wrote:
(snip)
Two additional questions though: 1) is there a way for a function to
get a reference to its caller automatically (as in, without the caller
having to pass it in)?
It's possible with sys._getframe() and a decorator - but consider it a
hack.
Gotcha, thanks.
and 2) what's the reason to use newstyle classes
versus the old?
All this is explained on python.org (there's a menu entry for this in
the documentation menu). AFAICT, newstyle classes can do whatever
oldstyle classes did, *and much more* (descriptors and usable
metaclasses) - and they are somewhat faster too. So - compatibility with
older Python versions ( 2.2 IIRC) set aside -, there's just no reason
to use oldstyle classes.
In order to create the dynamic class NewClass in the
code above I called type() but that requires at least one new style
class as a base. Thus, I had to have at least one of my animals inherit
from object and this seemed a nuisance since
OMG, eight more keystrokes - talk about a nuisance...
Like, Oh My God! *claps hand to mouth* lol You humor me. Yes, eight
more keystrokes. I follow the general rule of, if I'm going to put in
extra effort, I'd like to know why. So you see, it's not so much an
adversion to the eight keystrokes (multiplied by however many classes I
have mind you), but to not knowing why I should use them. If I don't
care for descriptors or metaclasses, I don't see why I should feel
compelled to use them. And when I decide I want/need these features, I
can put the eight keystroke in at that time. No biggy. :-) Thanks
Bruno.
I don't at this point
know what the benefit of newstyle classes is.
See it the other way round : the *only* benefit of oldstyle classes is
compatibility with pre-2.2 Python versions.
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DictProxy? What is this?
When I tried to update a class's __dict__, I got an error saying that there is no 'update' attribute for dictproxy object. What is a dictproxy object? I thought that __dict__ is always suppose to be a, no kidding, dictionary? Hence there should indeed be an update method. What's this proxy business? Thanks all. -- http://mail.python.org/mailman/listinfo/python-list
Re: DictProxy? What is this?
[EMAIL PROTECTED] wrote: When I tried to update a class's __dict__, I got an error saying that there is no 'update' attribute for dictproxy object. What is a dictproxy object? a CPython implementation detail, used to protect an internal data structure used by new-style objects from unexpected modifications. /F -- http://mail.python.org/mailman/listinfo/python-list
Re: DictProxy? What is this?
Fredrik Lundh wrote: [EMAIL PROTECTED] wrote: When I tried to update a class's __dict__, I got an error saying that there is no 'update' attribute for dictproxy object. What is a dictproxy object? a CPython implementation detail, used to protect an internal data structure used by new-style objects from unexpected modifications. /F Ah, so I'm not suppose to be able to change a class's __dict__? Thanks Fredrik. -- http://mail.python.org/mailman/listinfo/python-list
A game idea.
I have had what I think is quite a nice game idea, but I don't really have the experience or knowledge to go about it. Would anyone be willing to start a game project? The game I am thinking about is a virtual IRC stock exchange. There will be a bot in the channel which gets the live stock quotes and also adds any effects of buying or selling of the players. Everyone will have their own portfolio, which they will be able to view on the web, and will be able to issue commands from the irc channel. They'll be able to trade between eachother, and also to the stock exchange. I know this sounds like quite a big project, but I think this would be a highly fun game and maybe it would become quite popular. I would be willing to help of course with what I can, but obviously, an experienced developer would be needed. -- http://mail.python.org/mailman/listinfo/python-list
Re: Python database access
But I don't know how to make the connectivity or rather which module to import. Try mxODBC http://www.egenix.com/files/python/mxODBC.html -- http://mail.python.org/mailman/listinfo/python-list
Re: DictProxy? What is this?
Le lundi 26 juin 2006 16:06, [EMAIL PROTECTED] a écrit :
Fredrik Lundh wrote:
[EMAIL PROTECTED] wrote:
When I tried to update a class's __dict__, I got an error saying that
there is no 'update' attribute for dictproxy object. What is a
dictproxy object?
a CPython implementation detail, used to protect an internal data
structure used by new-style objects from unexpected modifications.
/F
Ah, so I'm not suppose to be able to change a class's __dict__? Thanks
Fredrik.
Of course, yes :
In [1]: class a(object) : pass
...:
In [2]: a.__dict__
Out[2]: dictproxy object at 0xa7e01d34
In [3]: a.__dict__.items()
Out[3]:
[('__dict__', attribute '__dict__' of 'a' objects),
('__module__', '__main__'),
('__weakref__', attribute '__weakref__' of 'a' objects),
('__doc__', None)]
In [4]: a.__dict__['foo'] = lambda s : True
---
exceptions.TypeError...
TypeError: object does not support item assignment
hmmm, not this way, but :
In [5]: a.foo = lambda s : True
In [6]: a.__dict__.items()
Out[6]:
[('__dict__', attribute '__dict__' of 'a' objects),
('__module__', '__main__'),
('foo', function lambda at 0xa79528ec),
('__weakref__', attribute '__weakref__' of 'a' objects),
('__doc__', None)]
In [7]: a().foo()
Out[7]: True
or :
In [9]: setattr(a, 'bar', lambda s : False)
In [10]: a().bar()
Out[10]: False
--
_
Maric Michaud
_
Aristote - www.aristote.info
3 place des tapis
69004 Lyon
Tel: +33 426 880 097
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Questions on Threading
Hello--I'm using the threading module to accomplish some distributed processing on a project, and have a basic (I hope) question that I can't find an answer to elsewhere.I've noted that there's a lot of documentation saying that there is no external way to stop a thread, and yet when creating a thread through the threading module I can see that it has a method called _Thread__stop, which does indeed stop it. Is this in any way dangerous ( i.e. doesn't actually stop the thread, or causes other thread timing issues down the road?) Or is there some other reason that there is officially no stop method?The code would be basically:t = threading.Thread (None, some_function)t.start()#Let t run for a whilet._Thread__stop()Is this dangerous to a system using several many threads (100 max)?Thanks,J.C.Sackett -- http://mail.python.org/mailman/listinfo/python-list
Re: DictProxy? What is this?
All right. Thanks for explaining that Maric.
Maric Michaud wrote:
Le lundi 26 juin 2006 16:06, [EMAIL PROTECTED] a écrit :
Fredrik Lundh wrote:
[EMAIL PROTECTED] wrote:
When I tried to update a class's __dict__, I got an error saying that
there is no 'update' attribute for dictproxy object. What is a
dictproxy object?
a CPython implementation detail, used to protect an internal data
structure used by new-style objects from unexpected modifications.
/F
Ah, so I'm not suppose to be able to change a class's __dict__? Thanks
Fredrik.
Of course, yes :
In [1]: class a(object) : pass
...:
In [2]: a.__dict__
Out[2]: dictproxy object at 0xa7e01d34
In [3]: a.__dict__.items()
Out[3]:
[('__dict__', attribute '__dict__' of 'a' objects),
('__module__', '__main__'),
('__weakref__', attribute '__weakref__' of 'a' objects),
('__doc__', None)]
In [4]: a.__dict__['foo'] = lambda s : True
---
exceptions.TypeError...
TypeError: object does not support item assignment
hmmm, not this way, but :
In [5]: a.foo = lambda s : True
In [6]: a.__dict__.items()
Out[6]:
[('__dict__', attribute '__dict__' of 'a' objects),
('__module__', '__main__'),
('foo', function lambda at 0xa79528ec),
('__weakref__', attribute '__weakref__' of 'a' objects),
('__doc__', None)]
In [7]: a().foo()
Out[7]: True
or :
In [9]: setattr(a, 'bar', lambda s : False)
In [10]: a().bar()
Out[10]: False
--
_
Maric Michaud
_
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3 place des tapis
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Tel: +33 426 880 097
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Re: languages with full unicode support
Oliver Bandel [EMAIL PROTECTED] wrote in message news:[EMAIL PROTECTED] Xah Lee wrote: As far as i know, Java and JavaScript are languages with full, complete unicode support. That is, they allow names to be defined using unicode. Can you explain what you mena with the names here? As in variable names, function names, class names, etc. - Oliver -- http://mail.python.org/mailman/listinfo/python-list
Get List of Classes
Is there a method or attribute I can use to get a list of classes defined or in-use within my python program? I tried using pyclbr and readmodule but for reason that is dogslow. Thanks in advance DigiO -- http://mail.python.org/mailman/listinfo/python-list
Search String for Word
What's the best way to search a string for a particular word and get a booleen value indicating whether it exists in the string or not? Thanks... -- http://mail.python.org/mailman/listinfo/python-list
Re: What is Expressiveness in a Computer Language [off-topic]
Matthias Blume wrote: I agree with Bob Harper about safety being language-specific and all that. But, with all due respect, I think his characterization of C is not accurate. [...] AFAIC, C is C-unsafe by Bob's reasoning. Agreed. Of course, C can be made safe quite easily: Define a state undefined that is considered safe and add a transition to undefined wherever necessary. I wouldn't say that was quite easy at all. C99 4 #2: # If a shall or shall not requirement that appears outside of a constraint # is violated, the behavior is undefined. Undefined behavior is otherwise # indicated in this International Standard by the words undefined behavior # *or by the omission of any explicit definition of behavior*. [...] In other words, to fix C to be a safe language (compatible with Standard C89 or C99), you first have to resolve all the ambiguities in the standard where the behaviour is *implicitly* undefined. There are a lot of them. -- David Hopwood [EMAIL PROTECTED] -- http://mail.python.org/mailman/listinfo/python-list
Re: Search String for Word
What's the best way to search a string for a particular word and get a booleen value indicating whether it exists in the string or not? substring = 'foo' targetstring = 'blah foo bar' substring in targetstring True if substring in targetstring: print 'yup' yup http://docs.python.org/lib/typesseq.html -tkc -- http://mail.python.org/mailman/listinfo/python-list
Re: 2Qs
2nd question: [snip] if x10 and y10 and z10 and summ(tritup(x,y,z)): print OK Others have already suggested you use the built-in sum() function. I'll suggest you don't need it at all, because it is redundant. If the sum is zero, either all three values are zero or at least one of the values is negative. In either case the first test will fail. There are no circumstances where each of x, y and z are greater than 10 but the sum is zero; nor are there any circumstances where the sum is zero but x, y and z are still all greater than 10. Unless, of course, the function tritup returns negative values. My guess is that the 10 tests are protecting the tritup function, and possibly should be moved there. Without the details of the function, I can't tell, but it may be incorrect to remove those tests. Which brings us to the other bit of advice - unit tests protect you from yourself and from those who optimize too quickly. -- http://mail.python.org/mailman/listinfo/python-list
Re: Formatted string to object
Thankyou everyone for help last time: The following works ok when setting a wx.lib.buttons.GenBitmapTextButton's disabled bitmap in using wxpython instead of this: self.b1.SetBitmapDisabled(self.yellow) i can use this: aaa = 1 result1 = eval(self.b%s.SetBitmapDisabled(self.yellow) % aaa) result YAY! How would i to achieve this with getattr() ? getattr(locals()['parent'], aaa)??? Why would this be better as recommended in previous post here http://groups.google.com.au/group/comp.lang.python/browse_frm/thread/2529515bc85cd954/c2f080b21d668081?q=janamarnum=1#c2f080b21d668081 Any help appreciated ta -- http://mail.python.org/mailman/listinfo/python-list
Re: Search String for Word
I thought I'd seen that somewhere! Thanks Tim. I was previously using re.search(substring, targetstring). Tim Chase wrote: What's the best way to search a string for a particular word and get a booleen value indicating whether it exists in the string or not? substring = 'foo' targetstring = 'blah foo bar' substring in targetstring True if substring in targetstring: print 'yup' yup http://docs.python.org/lib/typesseq.html -tkc -- http://mail.python.org/mailman/listinfo/python-list
Re: Python taught in schools?
Lawrence D'Oliveiro [EMAIL PROTECTED] wrote: In article [EMAIL PROTECTED], [EMAIL PROTECTED] (Alex Martelli) wrote: ... let's try some google searches and see the number of million hits...: But how reliable are those estimates of numbers of hits, anyway? More than once I've got a page showing something like Results 1 - 10 of about 36 hits, only to find that there were no more pages after the second one. If it could get estimates so wrong with such small numbers, how can you trust the large ones? If your experience in the matter dates from a few months ago (and most of us may have done Google searches for years, contributing to form our impressions) it may perhaps not be all that applicable any more, according to rumors from early this year (e.g. http://www.eweek.com/article2/0,1895,1916406,00.asp) and blogging notes by Matt Cutts at http://www.mattcutts.com/blog/bigdaddy/ . If you can give examples of a query which estimates the (small) number of results very badly, net of course of Duncan Booth's observation regarding Google's attempts to filter out near-duplicates, I'll be glad to look further into the matter (my group is Production Systems, just about as far from such issues as you can imagine -- rather, we write software to keep our clusters, networks c smoothly running, monitor them, and so forth -- but, of course, I do have friends over in Search Quality and related groups... fortunately, Google has so far managed to avoid much of the silos syndrome... so I'll be glad to check it out, but I do need specific examples!-). Alex -- http://mail.python.org/mailman/listinfo/python-list
Re: pypy-0.9.0: stackless, new extension compiler
Hi all! Michael Hudson wrote: The PyPy development team has been busy working and we've now packaged our latest improvements, completed work and new experiments as version 0.9.0, our fourth public release. Unfortunately the download links for the release tarballs did not work until very recently. They are now working though. You can download the 0.9 release of PyPy under: http://codespeak.net/download/pypy/pypy-0.9.0.tar.bz2 http://codespeak.net/download/pypy/pypy-0.9.0.tar.gz http://codespeak.net/download/pypy/pypy-0.9.0.zip For detailed notes about how to get started into the world of PyPy see here: http://codespeak.net/pypy/dist/pypy/doc/getting-started.html Sorry for the fuss and cheers, Carl Friedrich Bolz -- http://mail.python.org/mailman/listinfo/python-list
Dr. Dobb's Python-URL! - weekly Python news and links (Jun 26)
QOTW: In short, it's never what you think it is ;-) - timbot, probably on the subject of performance Real efficiency comes from elegant solutions, not optimized programs. Optimization is always just a few correctness-preserving transformations away. - Jonathan Sobel http://www.cs.indiana.edu/~jsobel/c455-c511.updated.txt Microsoft is (again) structuring its current marketing around platforms, and apparently Python is starting to show up in the campaigns: http://www.microsoft.com/presspass/press/2006/jun06/06-20MSRoboticsStudioPR.mspx Intel puts Python to good use in commercial program slicing: http://groups.google.com/group/comp.lang.python/browse_thread/thread/98cd59f90b169896/ Transcoding PVRs? Constructing collaborative whiteboards? Streaming multimedia in all directions? Apparently you can construct very impressive network-aware audiovisual applications *visually* with Kamaelia: http://groups.google.com/group/comp.lang.python/browse_thread/thread/36c89411fba299b6/ If you only care about advanced concurrency methods, pipeline- based methods, and componentry, well, that's in there, too, wrapped as Axon: http://groups.google.com/group/comp.lang.python/msg/7a5f189e886d9fc0 Discussion about the new Python icons might inspire a reader to try them: http://groups.google.com/group/comp.lang.python/browse_thread/thread/204f2792a882648d/ Wow: PyPy is up to 0.9.0: http://groups.google.com/group/comp.lang.python.announce/msg/6fa325e6c0cdd526 Life becomes more sophisticated than ever before: http://golly.sourceforge.net/ Timbot illustrates how an experienced file-comparer thinks about performance hacks (and Windows): http://groups.google.com/group/comp.lang.python/msg/15d45c2b268fa410 ... and how much deeper one can analyze recursion and numerics than merely the tastes great! less filling! level: http://groups.google.com/group/comp.lang.python/msg/e67403fcaa06c022 http://groups.google.com/group/comp.lang.python/msg/4451e63833a0c1c1 Everything Python-related you want is probably one or two clicks away in these pages: Python.org's Python Language Website is the traditional center of Pythonia http://www.python.org Notice especially the master FAQ http://www.python.org/doc/FAQ.html PythonWare complements the digest you're reading with the marvelous daily python url http://www.pythonware.com/daily Mygale is a news-gathering webcrawler that specializes in (new) World-Wide Web articles related to Python. http://www.awaretek.com/nowak/mygale.html While cosmetically similar, Mygale and the Daily Python-URL are utterly different in their technologies and generally in their results. For far, FAR more Python reading than any one mind should absorb, much of it quite interesting, several pages index much of the universe of Pybloggers. http://lowlife.jp/cgi-bin/moin.cgi/PythonProgrammersWeblog http://www.planetpython.org/ http://mechanicalcat.net/pyblagg.html comp.lang.python.announce announces new Python software. Be sure to scan this newsgroup weekly. http://groups.google.com/groups?oi=djqas_ugroup=comp.lang.python.announce Python411 indexes podcasts ... to help people learn Python ... Updates appear more-than-weekly: http://www.awaretek.com/python/index.html Steve Bethard, Tim Lesher, and Tony Meyer continue the marvelous tradition early borne by Andrew Kuchling, Michael Hudson and Brett Cannon of intelligently summarizing action on the python-dev mailing list once every other week. http://www.python.org/dev/summary/ The Python Package Index catalogues packages. http://www.python.org/pypi/ The somewhat older Vaults of Parnassus ambitiously collects references to all sorts of Python resources. http://www.vex.net/~x/parnassus/ Much of Python's real work takes place on Special-Interest Group mailing lists http://www.python.org/sigs/ Python Success Stories--from air-traffic control to on-line match-making--can inspire you or decision-makers to whom you're subject with a vision of what the language makes practical. http://www.pythonology.com/success The Python Software Foundation (PSF) has replaced the Python Consortium as an independent nexus of activity. It has official responsibility for Python's development and maintenance. http://www.python.org/psf/ Among the ways you can support PSF is with a donation. http://www.python.org/psf/donate.html Kurt B. Kaiser publishes a weekly report on faults and patches. http://www.google.com/groups?as_usubject=weekly%20python%20patch Although unmaintained
Re: What is Expressiveness in a Computer Language [off-topic]
David Hopwood [EMAIL PROTECTED] writes: Matthias Blume wrote: I agree with Bob Harper about safety being language-specific and all that. But, with all due respect, I think his characterization of C is not accurate. [...] AFAIC, C is C-unsafe by Bob's reasoning. Agreed. Of course, C can be made safe quite easily: Define a state undefined that is considered safe and add a transition to undefined wherever necessary. I wouldn't say that was quite easy at all. C99 4 #2: # If a shall or shall not requirement that appears outside of a constraint # is violated, the behavior is undefined. Undefined behavior is otherwise # indicated in this International Standard by the words undefined behavior # *or by the omission of any explicit definition of behavior*. [...] In other words, to fix C to be a safe language (compatible with Standard C89 or C99), you first have to resolve all the ambiguities in the standard where the behaviour is *implicitly* undefined. There are a lot of them. Yes, if you want to make the transition system completely explict, it won't be easy. I was thinking of a catch-all rule that says: transition to undefined unless specified otherwise. (Note that I am not actually advocating this approach to making a language safe. For practical purposes, C is unsafe. (And so is C++.)) -- http://mail.python.org/mailman/listinfo/python-list
Re: Get List of Classes
Is there a method or attribute I can use to get a list of classes defined or in-use within my python program? I tried using pyclbr and readmodule but for reason that is dogslow. Well, given that so much in python is considered a class, the somewhat crude code below walks an object/module and emits details regarding what's going on. I couldn't find any nice method for determining if a variable referenced a module other than checking to see if that item had both a __file__ and a __name__ attribute. Likewise, the check for whether something is an object is a bit crude. def inspect(thing, name = '', indent=0): ... if hasattr(thing, __file__) and hasattr(thing, __name__): ... #assume it's a module ... print %sModule %s % (\t * indent, thing.__name__) ... for subthing in dir(thing): ... objname = ..join([name, subthing]).lstrip(.) ... inspect(eval(objname), ... objname, indent+1) ... elif isinstance(thing, object): ... print %s%s is an object % (\t * indent, name) ... import m1 # m1 is a junk module that references module m2 and has # some junk classes in it inspect(m1, m1) Module m1 m1.M1Class is an object m1.M1ObjectClass is an object m1.__builtins__ is an object m1.__doc__ is an object m1.__file__ is an object m1.__name__ is an object Module m2 m1.m2.M2Class is an object m1.m2.M2ObjectClass is an object m1.m2.__builtins__ is an object m1.m2.__doc__ is an object m1.m2.__file__ is an object m1.m2.__name__ is an object You could also filter out builtin object properties by wrapping that last print statement in something like if not name.startswith(_): print ... which might cut down on some of the noise. Just a few ideas. -tkc -- http://mail.python.org/mailman/listinfo/python-list
Re: Python database access
The odbc module is part of the Python Standard Library. So you can search for docs on using it in the Python2x.chm help file (or the HTML version of the same docs) that comes with the Windows Python disttribution. Its quite easy to use ODBC from Python, at least for simple tasks like select * from tablename. Vasudev Ram http://www.geocities.com/vasudevram PDF conversion toolkt: http://sourceforge.net/projects/xtopdf BartlebyScrivener wrote: But I don't know how to make the connectivity or rather which module to import. Try mxODBC http://www.egenix.com/files/python/mxODBC.html -- http://mail.python.org/mailman/listinfo/python-list
Re: Search String for Word
And what if I want to search for an item in a tuple, is there a similarly easy method? Tim Chase wrote: What's the best way to search a string for a particular word and get a booleen value indicating whether it exists in the string or not? substring = 'foo' targetstring = 'blah foo bar' substring in targetstring True if substring in targetstring: print 'yup' yup http://docs.python.org/lib/typesseq.html -tkc -- http://mail.python.org/mailman/listinfo/python-list
Re: style question
Hari Sekhon wrote:
Is it better to do:
message = This is line1.
This is line2
This is line3\n
or
message = This is line1.\n
message = message + This is line2\n
message = message + This is line3\n
Since the first method does not follow python's clean and easy looking
indentation structure but the second just looks crude and ugly anyway.
If I indent the first version so the text is lined up to match code
indentation then this comes out in the input and isn't aligned there.
What about
message =
This is line 1
This is line 2
This is line 3
When it is necessary to skip first empty line):
message =
This is line 1
This is line 2
This is line 3
[1:]
When necessary to skip first line _and_ indentation:
message =
This is line 1
This is line 2
This is line 3
.replace('\n ', '\n')[1:] # adjust here '\n ' to indentation
# ^-- gives 'This is line 1\nThis is line 2\nThis is line 3\n'
?
Claudio
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Re: Termination and type systems
David Hopwood [EMAIL PROTECTED] wrote: Marshall wrote: David Hopwood wrote: A type system that required an annotation on all subprograms that do not provably terminate, OTOH, would not impact expressiveness at all, and would be very useful. Interesting. I have always imagined doing this by allowing an annotation on all subprograms that *do* provably terminate. Maybe the paper Linear types and non-size-increasing polynomial time computation by Martin Hofmann is interesting in this respect. From the abstract: We propose a linear type system with recursion operators for inductive datatypes which ensures that all definable functions are polynomial time computable. The system improves upon previous such systems in that recursive definitions can be arbitrarily nested; in particular, no predicativity or modality restrictions are made. It does not only ensure termination, but termination in polynomial time, so you can use those types to carry information about this as well. If the annotation marks not-provably-terminating subprograms, then it calls attention to those subprograms. This is what we want, since it is less safe/correct to use a nonterminating subprogram than a terminating one (in some contexts). That would be certainly nice, but it may be almost impossible to do in practice. It's already hard enough to guarantee termination with the extra information present in the type annotation. If this information is not present, then the language has to be probably restricted so severely to ensure termination that it is more or less useless. - Dirk -- http://mail.python.org/mailman/listinfo/python-list
Re: Get List of Classes
Wow, more than I had asked for, thank you Tim! I ended up doing this: def isClass(object): if 'classobj' in str(type(object)): return 1 elif 'type' in str(type(object)): return 1 else: return 0 def listClasses(): classes = [] for eachobj in globals().keys(): if isClass(globals()[eachobj]): classes.append(globals()[eachobj]) print eachobj return classes Tim Chase wrote: Is there a method or attribute I can use to get a list of classes defined or in-use within my python program? I tried using pyclbr and readmodule but for reason that is dogslow. Well, given that so much in python is considered a class, the somewhat crude code below walks an object/module and emits details regarding what's going on. I couldn't find any nice method for determining if a variable referenced a module other than checking to see if that item had both a __file__ and a __name__ attribute. Likewise, the check for whether something is an object is a bit crude. def inspect(thing, name = '', indent=0): ... if hasattr(thing, __file__) and hasattr(thing, __name__): ... #assume it's a module ... print %sModule %s % (\t * indent, thing.__name__) ... for subthing in dir(thing): ... objname = ..join([name, subthing]).lstrip(.) ... inspect(eval(objname), ... objname, indent+1) ... elif isinstance(thing, object): ... print %s%s is an object % (\t * indent, name) ... import m1 # m1 is a junk module that references module m2 and has # some junk classes in it inspect(m1, m1) Module m1 m1.M1Class is an object m1.M1ObjectClass is an object m1.__builtins__ is an object m1.__doc__ is an object m1.__file__ is an object m1.__name__ is an object Module m2 m1.m2.M2Class is an object m1.m2.M2ObjectClass is an object m1.m2.__builtins__ is an object m1.m2.__doc__ is an object m1.m2.__file__ is an object m1.m2.__name__ is an object You could also filter out builtin object properties by wrapping that last print statement in something like if not name.startswith(_): print ... which might cut down on some of the noise. Just a few ideas. -tkc -- http://mail.python.org/mailman/listinfo/python-list
Re: Python taught in schools?
In article [EMAIL PROTECTED], Mirco Wahab [EMAIL PROTECTED] wrote: Thus spoke Cameron Laird (on 2006-06-25 13:08): I'll gratuitously add that, even though I'm personally fond of C++, I think teaching it as is done in colleges and high schools (!) amounts to child abuse. It's wildly inappropriate. C++ programming requires you to massively invest your thinking first into the setup of your build environment (can only be beaten by Java here). A while back I had the opportunity to teach a section of an introductory computer science course in C++. They had recently abandoned Pascal in favor of C++ as the language of choice. There was certainly some spinup on the development environment to do, but it wasn't too terrible. I think the real problem with C++ is that there is a lot of conceptual baggage to work around to get to a useful program without having the students unlearn things later. Just basic things like const (in its various forms), pointers vs. references, class basics, headers, etc., are necessary for idiomatic C++ programming, but they get in the way of teaching more basic concepts of program construction. I understand that the school switched to Java a short time later, which is some improvement, but still has a good bit of baggage. Now the Schemers have taken over, so they teach Scheme as the introductory language. One thing about Scheme is that it doen't have a lot of baggage; there is no room for it in the spec. :-) To return to topicality for a moment, I think exposing new students to a combination of Scheme and Python might work well, providing different views of how to build programs, and leaving the students with both theoretical and practical foundations on which to build. Gary Duzan Motorola CHS p.s. Then sock them with ML or Haskell to weed out the weak ones. ;-) Then if they survive Occam, throw Java at them, so they'll know what they are missing but can still get a job... -- http://mail.python.org/mailman/listinfo/python-list
Re: Get List of Classes
Le lundi 26 juin 2006 17:25, Tim Chase a écrit : I couldn't find any nice method for determining if a variable referenced a module other than checking to see if that item had both a __file__ and a __name__ attribute. Why not : In [8]: import types, sys In [9]: isinstance(sys, types.ModuleType) Out[9]: True ? Seems rather explicit IMO. -- _ Maric Michaud _ Aristote - www.aristote.info 3 place des tapis 69004 Lyon Tel: +33 426 880 097 -- http://mail.python.org/mailman/listinfo/python-list
Re: Search String for Word
On 26 Jun 2006 08:24:54 -0700, [EMAIL PROTECTED]
[EMAIL PROTECTED] wrote:
And what if I want to search for an item in a tuple, is there a
similarly easy method?
Tim Chase wrote:
What's the best way to search a string for a particular word and get a
booleen value indicating whether it exists in the string or not?
substring = 'foo'
targetstring = 'blah foo bar'
substring in targetstring
True
if substring in targetstring: print 'yup'
yup
t = ('a', 'b', 'c', 'd', 'e')
a = 'a'
a in t
True
y = 'y'
y in t
False
t = ('test', 'black', 'white')
a = 'a'
[i for i in t if a in i]
['black']
HTH :)
--
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Re: Get List of Classes
I couldn't find any nice method for determining if a variable referenced a module other than checking to see if that item had both a __file__ and a __name__ attribute. Why not : In [8]: import types, sys In [9]: isinstance(sys, types.ModuleType) Out[9]: True Yes...this is the best way to do it. I hadn't explored (or even noticed, before your reply) the types module, which seems to have a large toolset for doing exactly what I wanted to. Thanks! A good programming language has users asking how did I miss that? rather than why can't I make it do what I want?. Yet another feather in Python's cap. -tkc -- http://mail.python.org/mailman/listinfo/python-list
Replace Whole Object Through Object Method
How can an object replace itself using its own method? See the
following code:
class Mixin:
def mixin(object, *classes):
NewClass = type('Mixin', (object.__class__,) + classes, {})
newobj = NewClass()
newobj.__dict__.update(object.__dict__)
return newobj
def isClass(object):
if 'classobj' in str(type(object)):
return 1
elif 'type' in str(type(object)):
return 1
else:
return 0
def listClasses():
classes = []
for eachobj in globals().keys():
if isClass(globals()[eachobj]):
classes.append(globals()[eachobj])
print eachobj
return classes
def MixInto(Class, Mixin):
if Mixin not in Class.__bases__:
Class.__bases__ += (Mixin,)
Okay, so the mixin function becomes part of whatever class I choose and
hence its instances, but the problem is that the way I currently have
it setup mixin() returns a new object, instead of replacing whatever
class instance that calls it into that new object. I hope I'm making
sense here.
Basically what I need is for the method to be able to find out the name
of the instance, then I can just go to the globals dictionary to do the
replacement.
Advance thanks to all who can help...
--
http://mail.python.org/mailman/listinfo/python-list
Re: Pygame.draw challenge is over!
Hey, just a quick note... when I visit http://pyweek.org I get a message that the site is not configured. www.pyweek.org works as expected. When I received this e-mail my e-mail client made pyweek.org clickable which is how I noticed the problem. On 6/25/06, [EMAIL PROTECTED] [EMAIL PROTECTED] wrote: It was quite successful too! Download the submissions from the pyweek.org site: http://media.pyweek.org/static/pgd-200606.zip Congratulations to all who participated! Richard -- Visit the PyWeek website: http://www.pyweek.org/ -- http://mail.python.org/mailman/listinfo/python-announce-list Support the Python Software Foundation: http://www.python.org/psf/donations.html -- Matthew Nuzum www.bearfruit.org -- http://mail.python.org/mailman/listinfo/python-list
Re: Search String for Word
Thank you thank you!
Tim Williams wrote:
On 26 Jun 2006 08:24:54 -0700, [EMAIL PROTECTED]
[EMAIL PROTECTED] wrote:
And what if I want to search for an item in a tuple, is there a
similarly easy method?
Tim Chase wrote:
What's the best way to search a string for a particular word and get a
booleen value indicating whether it exists in the string or not?
substring = 'foo'
targetstring = 'blah foo bar'
substring in targetstring
True
if substring in targetstring: print 'yup'
yup
t = ('a', 'b', 'c', 'd', 'e')
a = 'a'
a in t
True
y = 'y'
y in t
False
t = ('test', 'black', 'white')
a = 'a'
[i for i in t if a in i]
['black']
HTH :)
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Re: What is Expressiveness in a Computer Language
Marshall wrote: I stand corrected: if one is using C and writing self-modifying code, then one *can* zip one's pants. Static proofs notwithstanding, I'd prefer a dynamic check just prior to this operation. I want my code to be the only self-modifying thing around here. -- http://mail.python.org/mailman/listinfo/python-list
Re: Mix-In Class Methods At Run-Time
[EMAIL PROTECTED] wrote:
Bruno Desthuilliers wrote:
[EMAIL PROTECTED] wrote:
(snip)
and 2) what's the reason to use newstyle classes
versus the old?
All this is explained on python.org (there's a menu entry for this in
the documentation menu). AFAICT, newstyle classes can do whatever
oldstyle classes did, *and much more* (descriptors and usable
metaclasses) - and they are somewhat faster too. So - compatibility with
older Python versions ( 2.2 IIRC) set aside -, there's just no reason
to use oldstyle classes.
In order to create the dynamic class NewClass in the
code above I called type() but that requires at least one new style
class as a base. Thus, I had to have at least one of my animals inherit
from object and this seemed a nuisance since
OMG, eight more keystrokes - talk about a nuisance...
Like, Oh My God! *claps hand to mouth* lol You humor me. Yes, eight
more keystrokes. I follow the general rule of, if I'm going to put in
extra effort,
OMG, eight more keystrokes - talk about extra effort !-)
I'd like to know why.
The only reason for *not* doing it would be compat issues with pre 2.2.x
versions.
So you see, it's not so much an
adversion to the eight keystrokes (multiplied by however many classes I
have mind you),
Strange enough, I do write my share of Python code, and don't even
notice typing the EightKeystrokes.
but to not knowing why I should use them.
Because they are kind of the standard Python object model since 2.2.x ?-)
Did you at least take time to read the doc on newstyle classes on
python.org ?
FWIW, with 2.5, even exceptions are now newstyle classes. No more
oldstyle classes in the builtins. And AFAICT, no more oldstyle classes
in the standard lib neither. Does that ring a bell ?
If I don't
care for descriptors or metaclasses,
You *do* care for descriptors. Without descriptors, no properties, no
classmethods, no staticmethods... What a desolation :(
More seriously, given what you're into actually, not caring about what
one can do with newstyle classes seems really strange to me - like
digging a swimming-pool with a pick and a shovel when you have an
excavator... (disclaimer : google translation, not sure it makes sens in
english...)
I don't see why I should feel
compelled to use them.
them - newstyle classes or descriptors and metaclasses ?
And when I decide I want/need these features, I
can put the eight keystroke in at that time.
What can I say ? That's your code, not mine...
--
bruno desthuilliers
python -c print '@'.join(['.'.join([w[::-1] for w in p.split('.')]) for
p in '[EMAIL PROTECTED]'.split('@')])
--
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Re: Replace Whole Object Through Object Method
Le lundi 26 juin 2006 17:57, [EMAIL PROTECTED] a écrit :
How can an object replace itself using its own method? See the
following code:
class Mixin:
def mixin(object, *classes):
NewClass = type('Mixin', (object.__class__,) + classes, {})
newobj = NewClass()
newobj.__dict__.update(object.__dict__)
return newobj
Variables in python are names, not the objects, and instances shouldn't know
nothing about how they are referenced.
I guess what you want to do is, in fact, very simple somethig like :
a = SomeClass()
a = a.some_method_wich_return_a_new_object()
or :
for k, v in globals().iteritems() :
if isinstance(v, SomeClass) :
globlals()[k] = v.some_method_wich_return_a_new_object()
def isClass(object):
Don't mask builtin names.
if 'classobj' in str(type(object)):
Why don't you test the type directly ?
return 1
Python has boolean for clarity.
elif 'type' in str(type(object)):
return 1
else:
return 0
should be :
import types
def isClass(object_) :
if isinstance(object_, type) :
return True # new style class
elif isinstance(object_, types.ClassType) :
return True # old-style class
else : return False
or if you don't need to diferentiate the cases :
def isClass(object_) :
return isinstance(object_, type) or \
isinstance(object_, types.ClassType)
def listClasses():
classes = []
for eachobj in globals().keys():
if isClass(globals()[eachobj]):
classes.append(globals()[eachobj])
print eachobj
return classes
def MixInto(Class, Mixin):
if Mixin not in Class.__bases__:
Class.__bases__ += (Mixin,)
This doesn't work in most cases (with new style classes), better recreat a
type which inherit from Class and Mixin, or Class.__dict__ with
Mixin.__dict__.
Okay, so the mixin function becomes part of whatever class I choose and
hence its instances, but the problem is that the way I currently have
it setup mixin() returns a new object, instead of replacing whatever
class instance that calls it into that new object. I hope I'm making
sense here.
Basically what I need is for the method to be able to find out the name
of the instance, then I can just go to the globals dictionary to do the
replacement.
Advance thanks to all who can help...
--
_
Maric Michaud
_
Aristote - www.aristote.info
3 place des tapis
69004 Lyon
Tel: +33 426 880 097
--
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Re: What is Expressiveness in a Computer Language
David Hopwood wrote: Joe Marshall wrote: I do this quite often. Sometimes I'll develop `in the debugger'. I'll change some piece of code and run the program until it traps. Then, without exiting the debugger, I'll fix the immediate problem and restart the program at the point it trapped. This technique takes a bit of practice, but if you are working on something that's complex and has a lot of state, it saves a lot of time because you don't have to reconstruct the state every time you make a change. The problem with this is that from that point on, what you're running is neither the old nor the new program, since its state may have been influenced by the bug before you corrected it. Yes. The hope is that it is closer to the new program than to the old. I find it far simpler to just restart the program after correcting anything. If this is too difficult, I change the design to make it less difficult. In the most recent case where I was doing this, I was debugging transaction rollback that involved multiple database extents. It was somewhat painful to set up a clean database to the point where I wanted to try the rollback, and I wanted a pristine database for each trial so I could examine the raw bits left by a rollback. It was pretty easy to deal with simple errors in the debugger, so I chose to do that instead. Wow, interesting. (I say the following only to point out differing strategies of development, not to say one or the other is right or bad or whatever.) I occasionally find myself doing the above, and when I do, I take it as a sign that I've screwed up. I find that process excruciating, and I do everything I can to avoid it. Over the years, I've gotten more and more adept at trying to turn as many bugs as possible into type errors, so I don't have to run the debugger. Now, there might be an argument to be made that if I had been using a dynamic language, the process wouldn't be so bad, and I woudn't dislike it so much. But mabe: As a strawman: suppose there are two broad categories of mental strategies for thinking about bugs, and people fall naturally into one way or the other, the way there are morning people and night people. One group is drawn to the static analysis, one group hates it. One group hates working in the debugger, one group is able to use that tool very effectively and elegantly. Anyway, it's a thought. I don't buy this -- or at least, I am not in either group. A good debugger is invaluable regardless of your attitude to type systems. Recently I was debugging two programs written to do similar things in the same statically typed language (C), but where a debugger could not be used for one of the programs. It took maybe 5 times longer to find and fix each bug without the debugger, and I found it a much more frustrating experience. -- David Hopwood [EMAIL PROTECTED] -- http://mail.python.org/mailman/listinfo/python-list
Re: Replace Whole Object Through Object Method
[EMAIL PROTECTED] wrote:
How can an object replace itself using its own method?
AFAIK, It can't (but I can be wrong - some guru around ?).
See the
following code:
class Mixin:
def mixin(object, *classes):
NewClass = type('Mixin', (object.__class__,) + classes, {})
newobj = NewClass()
newobj.__dict__.update(object.__dict__)
return newobj
def isClass(object):
if 'classobj' in str(type(object)):
return 1
elif 'type' in str(type(object)):
return 1
else:
return 0
def listClasses():
classes = []
for eachobj in globals().keys():
if isClass(globals()[eachobj]):
classes.append(globals()[eachobj])
print eachobj
return classes
FWIW:
Python 2.4.3 (#1, Jun 3 2006, 17:26:11)
[GCC 3.4.6 (Gentoo 3.4.6-r1, ssp-3.4.5-1.0, pie-8.7.9)] on linux2
Type help, copyright, credits or license for more information.
def dumbfactory():
... class Dumb(object): pass
... class Dummy: pass
... return Dumb, Dummy
...
globals()
{'__builtins__': module '__builtin__' (built-in), '__name__':
'__main__', '__doc__': None, 'dumbfactory': function dumbfactory at
0x2ab66e60}
def fun():
... dumb, dummy = dumbfactory()
... return
...
fun()
globals()
{'__builtins__': module '__builtin__' (built-in), '__name__':
'__main__', 'fun': function fun at 0x2ab66ed8, '__doc__': None,
'dumbfactory': function dumbfactory at 0x2ab66e60}
Looks like dumb and dummy won't get listed... And also:
class Mymeta(type):
... pass
...
class Foo(object):
... __metaclass__ = Mymeta
...
'type' in str(type(globals()['Mymeta']))
True
Looks like this will list metaclasses too... May or may not be a problem...
def MixInto(Class, Mixin):
You're aware that in this function's scope, the 'Mixin' arg name will
shadow the Mixin class name ? (sorry for asking dumb question).
if Mixin not in Class.__bases__:
Class.__bases__ += (Mixin,)
Okay, so the mixin function becomes part of whatever class I choose and
hence its instances, but the problem is that the way I currently have
it setup mixin() returns a new object, instead of replacing whatever
class instance that calls it into that new object. I hope I'm making
sense here.
Basically what I need is for the method to be able to find out the name
of the instance, then I can just go to the globals dictionary to do the
replacement.
Advance thanks to all who can help...
Instead of exposing problems with your solution, you may want to expose
the real use case ?
--
bruno desthuilliers
python -c print '@'.join(['.'.join([w[::-1] for w in p.split('.')]) for
p in '[EMAIL PROTECTED]'.split('@')])
--
http://mail.python.org/mailman/listinfo/python-list
Re: Replace Whole Object Through Object Method
Maric Michaud wrote:
Le lundi 26 juin 2006 17:57, [EMAIL PROTECTED] a écrit :
How can an object replace itself using its own method? See the
following code:
class Mixin:
def mixin(object, *classes):
NewClass = type('Mixin', (object.__class__,) + classes, {})
newobj = NewClass()
newobj.__dict__.update(object.__dict__)
return newobj
Variables in python are names, not the objects, and instances shouldn't know
nothing about how they are referenced.
I guess what you want to do is, in fact, very simple somethig like :
a = SomeClass()
a = a.some_method_wich_return_a_new_object()
or :
for k, v in globals().iteritems() :
if isinstance(v, SomeClass) :
globlals()[k] = v.some_method_wich_return_a_new_object()
def isClass(object):
Don't mask builtin names.
You mean object? The shadow/mask only exists within the scope of the
function. But anyhow, point well taken.
if 'classobj' in str(type(object)):
Why don't you test the type directly ?
Thanks.
return 1
Python has boolean for clarity.
Thanks.
elif 'type' in str(type(object)):
return 1
else:
return 0
should be :
import types
def isClass(object_) :
if isinstance(object_, type) :
return True # new style class
elif isinstance(object_, types.ClassType) :
return True # old-style class
else : return False
or if you don't need to diferentiate the cases :
def isClass(object_) :
return isinstance(object_, type) or \
isinstance(object_, types.ClassType)
Very clean! Thank you.
def listClasses():
classes = []
for eachobj in globals().keys():
if isClass(globals()[eachobj]):
classes.append(globals()[eachobj])
print eachobj
return classes
def MixInto(Class, Mixin):
if Mixin not in Class.__bases__:
Class.__bases__ += (Mixin,)
This doesn't work in most cases (with new style classes), better recreat a
type which inherit from Class and Mixin, or Class.__dict__ with
Mixin.__dict__.
What doesn't work exactly? The whole purpose of the mixin is to add
functionality to the class and hence to all its instances on the fly.
Creating a new type would not achieve this, unless there's something
I'm missing (a very real possibility!). And what do you mean doesn't
work in most newstyleclass cases? Seems to be working just fine...
Okay, so the mixin function becomes part of whatever class I choose and
hence its instances, but the problem is that the way I currently have
it setup mixin() returns a new object, instead of replacing whatever
class instance that calls it into that new object. I hope I'm making
sense here.
Basically what I need is for the method to be able to find out the name
of the instance, then I can just go to the globals dictionary to do the
replacement.
Any answers my primary question though?
Advance thanks to all who can help...
--
_
Maric Michaud
_
Aristote - www.aristote.info
3 place des tapis
69004 Lyon
Tel: +33 426 880 097
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Re: style question
Claudio Grondi wrote:
clever stuff to di indentation
When necessary to skip first line _and_ indentation:
message =
This is line 1
This is line 2
This is line 3
.replace('\n ', '\n')[1:] # adjust here '\n ' to indentation
Riffing on this idea:
message =
This is line 1
This is line 2
This is line 3
.replace(
, '\n')[1:]
--Scott David Daniels
[EMAIL PROTECTED]
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Beginner Programmer Question
I am doing alot of reading and trying to teach myself how to program. I can not figure out how to make Write a program that continually reads in numbers from the user and adds them together until the sum reaches 100. this work. If someone could show me the correct code so i can learn from that it would be much appreciated. Thanks -- http://mail.python.org/mailman/listinfo/python-list
Re: Replace Whole Object Through Object Method
Bruno Desthuilliers wrote:
[EMAIL PROTECTED] wrote:
How can an object replace itself using its own method?
AFAIK, It can't (but I can be wrong - some guru around ?).
...
FWIW:
Python 2.4.3 (#1, Jun 3 2006, 17:26:11)
[GCC 3.4.6 (Gentoo 3.4.6-r1, ssp-3.4.5-1.0, pie-8.7.9)] on linux2
Type help, copyright, credits or license for more information.
def dumbfactory():
... class Dumb(object): pass
... class Dummy: pass
... return Dumb, Dummy
...
globals()
{'__builtins__': module '__builtin__' (built-in), '__name__':
'__main__', '__doc__': None, 'dumbfactory': function dumbfactory at
0x2ab66e60}
def fun():
... dumb, dummy = dumbfactory()
... return
...
fun()
globals()
{'__builtins__': module '__builtin__' (built-in), '__name__':
'__main__', 'fun': function fun at 0x2ab66ed8, '__doc__': None,
'dumbfactory': function dumbfactory at 0x2ab66e60}
Looks like dumb and dummy won't get listed... And also:
class Mymeta(type):
... pass
...
class Foo(object):
... __metaclass__ = Mymeta
...
'type' in str(type(globals()['Mymeta']))
True
Looks like this will list metaclasses too... May or may not be a problem...
def MixInto(Class, Mixin):
You're aware that in this function's scope, the 'Mixin' arg name will
shadow the Mixin class name ? (sorry for asking dumb question).
No sorry necessary, but yes, I am aware of it. Poor programming
practice I'm sure...
...
Basically what I need is for the method to be able to find out the name
of the instance, then I can just go to the globals dictionary to do the
replacement.
Advance thanks to all who can help...
Instead of exposing problems with your solution, you may want to expose
the real use case ?
***
I'm working with a team that's doing social modeling, and for example,
I need to model workers that at some point in the program may or may
not also become employers. Now, I want the workers to take on all
behaviors and attributes of an employer in addition to their
pre-existing worker behaviors and attributes. Also, as I'm sure you
guessed, the workers' attributes need to retain their values at that
point in the program, so a brand new worker-employer object wouldn't in
itself do the trick.
***
--
bruno desthuilliers
python -c print '@'.join(['.'.join([w[::-1] for w in p.split('.')]) for
p in '[EMAIL PROTECTED]'.split('@')])
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VPW: Talk schedule available
What's New? === The talk schedule for the Vancouver Python Workshop is now available: http://www.vanpyz.org/conference/talkschedule.html This years line-up might be even stronger than in 2004, so check it out! About the Vancouver Python Workshop === The conference will begin with keynote addresses on August 4st by Guido van Rossum [1] and Jim Hugunin [2]. Further talks (and tutorials for beginners) will take place on August 5th and 6th. Ian Cavén [3] will give the closing address. The Vancouver Python Workshop is a community organized and designed for both the beginner and for the experienced Python programmer with: * tutorials for beginning programmers * advanced lectures for Python experts * case studies of Python in action * after-hours social events * informative keynote speakers * tracks on multimedia, Web development, education and more More information see: http://www.vanpyz.org/conference/ or contact Brian Quinlan at: [EMAIL PROTECTED] Vancouver = In addition to the opportunity to learn and socialize with fellow Pythonistas, the Vancouver Python Workshop also gives visitors the opportunity to visit one of the most extraordinary cities in the world [4]. For more information about traveling to Vancouver, see: http://www.vanpyz.org/conference/vancouver.html http://www.tourismvancouver.com http://en.wikipedia.org/wiki/Vancouver Important dates === Talk proposals accepted: May 15th to June 15th Early registration (discounted): May 22nd to June 30th Normal registration: from July 1st Keynotes: August 4th Conference and tutorial dates: August 5th and 6th [1] Guido van Rossum (Google) is the inventor of Python and has managed its growth and development for more than a decade. Guido was awarded the Free Software Foundation Award in 2002 and Dr.Dobb's 1999 Excellence in Programming Award. Guido works at Google and spends half of his time on Python. [2] Jim Hugunin (Microsoft) is the creator of numerous innovations that take Python into new application domains. Jim's most recent project, IronPython integrates Python into Microsoft's .NET runtime. Jim's previous project, Jython is Python for the Java runtime and was the second production-quality implementation of Python. Before that, Jim's Numeric Python adapted Python to the needs of number crunching applications. Jim works at Microsoft adapting the .NET runtime to the needs of dynamic languages like Python. [3] Ian Cavén is the primary developer of the Lowry Digital Images motion picture restoration system. This Python and Zope-based system has been used to restore over 150 motion pictures. Highlights include Citizen Kane, Sunset Boulevard and both the Indiana Jones and Star Wars trilogies. While Ian was Chief Scientist at Lowry Digital, his rack of computers grew from a few Macintoshes on his desktop to over six hundred Macintosh and Linux servers - at one point earning Lowry the title as the second biggest installation of parallel processing Maintoshes in the world. In 2005, Lowry Digital Images was acquired by DTS (the famous movie audio company) and renamed DTS Digital Images. The motion picture restoration system has been discussed in publications as diverse as IEEE Spectrum, USA Today, the BBC NEWS, the New York Times and Apple.com. Ian has been a Python enthusiast since 1999. [4] http://news.bbc.co.uk/2/hi/business/2299119.stm http://edition.cnn.com/2006/BUSINESS/06/15/btn.cities/index.html Cheers, Brian -- http://mail.python.org/mailman/listinfo/python-list
Re: Beginner Programmer Question
[EMAIL PROTECTED] wrote: I am doing alot of reading and trying to teach myself how to program. I can not figure out how to make Write a program that continually reads in numbers from the user and adds them together until the sum reaches 100. this work. If someone could show me the correct code so i can learn from that it would be much appreciated. Thanks Isn't it your homework? Why can't you figure it out? What have you tried? Claudio -- http://mail.python.org/mailman/listinfo/python-list
Re: Beginner Programmer Question
Claudio Grondi wrote: [EMAIL PROTECTED] wrote: I am doing alot of reading and trying to teach myself how to program. I can not figure out how to make Write a program that continually reads in numbers from the user and adds them together until the sum reaches 100. this work. If someone could show me the correct code so i can learn from that it would be much appreciated. Thanks Isn't it your homework? Why can't you figure it out? What have you tried? Claudio I am doing alot of reading, and the problem didnt come with an answer. I dont understand how to get it to continually input numbers and add all those together -- http://mail.python.org/mailman/listinfo/python-list
Re: Beginner Programmer Question
[EMAIL PROTECTED] wrote: Claudio Grondi wrote: [EMAIL PROTECTED] wrote: I am doing alot of reading and trying to teach myself how to program. I can not figure out how to make Write a program that continually reads in numbers from the user and adds them together until the sum reaches 100. this work. If someone could show me the correct code so i can learn from that it would be much appreciated. Thanks Isn't it your homework? Why can't you figure it out? What have you tried? Claudio I am doing alot of reading, and the problem didnt come with an answer. I dont understand how to get it to continually input numbers and add all those together #Add up to 100 program #What number are you adding up to? bigone = 100 number = input(Whats the first number?) number2 = input (Whats the second number?) nu3 = number+number2 while nu3 bigone: print (Not there yet, next number please) print Finally there! thats what i thought maybe it was...but after the first two numbers it just continually scrolls on the screen with finally there -- http://mail.python.org/mailman/listinfo/python-list
Re: Beginner Programmer Question
I am doing alot of reading, and the problem didnt come with an answer. I dont understand how to get it to continually input numbers and add all those together Use while, raw_input, sys.argv[1] and int() and break the loop when the sum is above 100. ;-) -- http://mail.python.org/mailman/listinfo/python-list
