Re: Mutable objects inside tuples - good or bad?
Am 06.04.2014 09:25, schrieb Gary Herron: On 04/05/2014 11:53 PM, John Ladasky wrote: I find this programming pattern to be useful... but can it cause problems? No. What kind of problems are you considering? It won't break Python. It's perfectly legal code. The tuple c is still immutable, consisting of two specific objects, and (as always) without regard to the specifics or contents of those two objects. It seems a tuple's immutability is debatable, or is this another instance of the small-integer-reuse-implementation-detail-artifact? Python 2.6.6 (r266:84292, Dec 26 2010, 22:31:48) [GCC 4.4.5] on linux2 Type help, copyright, credits or license for more information. a = ([1,2],[3,4]) b = a a is b True a == b True c = (1,2,3) d = (1,2,3) c is d False c == d True cheers Paul -- https://mail.python.org/mailman/listinfo/python-list
Re: Mutable objects inside tuples - good or bad?
Am 07.04.2014 17:44, schrieb Chris Angelico: On Tue, Apr 8, 2014 at 1:26 AM, Paul Kölle pkoe...@gmail.com wrote: It seems a tuple's immutability is debatable, or is this another instance of the small-integer-reuse-implementation-detail-artifact? Python 2.6.6 (r266:84292, Dec 26 2010, 22:31:48) [GCC 4.4.5] on linux2 Type help, copyright, credits or license for more information. a = ([1,2],[3,4]) b = a a is b True a == b True c = (1,2,3) d = (1,2,3) c is d False c == d True That's nothing to do with mutability or reuse. With a and b, you assigned one to be the same as the other, so they are by definition identical (and equal; tuples assume that identity implies equality, even though that may not be true of their elements). With c and d, you assigned separate tuples, so they're allowed to be separate objects. I'm not sure if they're allowed to be constant-folded, but CPython apparently isn't doing so. They are still equal, though; they contain equal elements, ergo they are equal. (Note that (1, 2, 3) and (1.0, 2.0, 3.0) are equal, but they obviously can't be identical any more than 1 is 1.0 can ever be True.) ChrisA Thanks Chris, stupid error indeed ;) cheers Paul -- https://mail.python.org/mailman/listinfo/python-list
Re: Kivy for Python 3.3
Am 11.07.2013 16:26, schrieb fronag...@gmail.com: [scnipp] C:\MinGW\bin\gcc.exe -mdll -O -Wall -IC:\Python33\include -IC:\Python33\include -c kivy\graphics\vertex_instructions.c -o build\temp.win32-3.3\Release\kivy\grap hics\vertex_instructions.o In file included from kivy\graphics\vertex_instructions.c:314:0: kivy\graphics\/gl_redirect.h:8:22: fatal error: GL/glew.h: No such file or direc tory compilation terminated. error: command 'gcc' failed with exit status 1 Working on the reasoning that sticking the missing file into the python3.3\libs file worked, I tried adding the glew files (glew32.dll, glew32.lib, GL\glew and GL\wglew.h) there, however, it doesn't seem to have made a difference. And this I googled this before asking. Doesn't seem to be much. Hi, I can feel your pain beeing dragged into compile-unknown-source-on-windows from an innocent looking python script ;) This time it's not the linker complaining but GCC (the compiler) itself not being able to find the header file GL/glew.h. Headers are searched in the so called include path which is specified in setup.py. This link http://glew.sourceforge.net/install.html suggests glew.h is part of VisualStudio, and has some other interesting information. hth Paul -- http://mail.python.org/mailman/listinfo/python-list
Re: Kivy for Python 3.3
Am 11.07.2013 11:09, schrieb fronag...@gmail.com: Hello, first time poster here, and general newbie to Python. I'm looking to write a program in Python, (and have in fact written most of it by now,) and am trying to put together a GUI for it. Kivy looks very nice, particularly with the fact that it's supposed to be compatible with most platforms (including Android, which I would like to be able to use my program on in addition to running it on my desktop) with minimal hassle. However, its current iteration is Python 2.7 only, and I've only learned Python 3.3. [ snipp ] C:\MinGW\bin\..\lib\gcc\mingw32\3.4.5\..\..\..\..\mingw32\bin\ld.exe: cannot fin d -lmsvcr100 collect2: ld returned 1 exit status error: command 'gcc' failed with exit status 1 It might help copying msvcr100.dll (from MS VC++ Redistributable Package) to c:\python33\libs (or wherever your python install is). See http://bugs.python.org/issue15315 msg191106 hth Paul -- http://mail.python.org/mailman/listinfo/python-list
Re: Apache and suexec issue that wont let me run my python script
Am 01.06.2013 07:30, schrieb Νικόλαος Κούρας: [snipp] [Thu May 30 15:29:33 2013] [error] [client 46.12.46.11] suexec failure: could not open log file [Thu May 30 15:29:33 2013] [error] [client 46.12.46.11] fopen: Permission denied [Thu May 30 15:29:33 2013] [error] [client 46.12.46.11] Premature end of script headers: koukos.py [Thu May 30 15:29:33 2013] [error] [client 46.12.46.11] File does not exist: /home/nikos/public_html/500.shtml when i tail -F /usr/local/apache/logs/error_log What this error means? It appears that the effective user of the script does not have permission to open the log file that the suexec call requires. Yes, so which logfile and what user is suexec using to run your script? You should be able to answer all this from your apache configuration. cheers Paul -- http://mail.python.org/mailman/listinfo/python-list
Re: accessing an OLE Automation (IDispatch) server from python which requires the use of out params
Hi, Am 10.12.2012 20:13, schrieb bitbucket: I have an existing Windows application which provides an OLE Automation (IDispatch) interface. I'm not able to change that interface. I'd like to call it from a scripting language. I figure this would provide a nice quick way to invoke on the app. I initially tried this with Windows Powershell but ran into the following problem. I was able to create the object and invoke simple methods on it. However the interface for this app has methods which take out params. i.e. you pass in a reference to a variable and the server fills in the value. I couldn't get that to work. I finally gave up and decided it was just a limitation of Powershell, not being able to work with those out params. [snipp] Before switching technologies I'd check if this solves your problem http://geekswithblogs.net/Lance/archive/2009/01/14/pass-by-reference-parameters-in-powershell.aspx TL;DR IMHO out parameters are basically pointers (pass by reference) and need to be passed like GetSettingValue(name, [ref]$value)... cheers Paul -- http://mail.python.org/mailman/listinfo/python-list
Re: Help accessing COM .dll from Python
Hi, Am 01.12.2012 10:51, schrieb Steve Simmons: First time post - be gentle with me :-) I am trying to write a Python script to access a scanning device. I have an SDK for the scanner but the documentation is a bit limited and the supplier doesn't support Python (but Python is the best option for me in the current circumstances). From a quick view it seems the documentation is excellent. There are tons of examples (even Java so you could use jython), API documents and the SDK. The VC SDK.pdf from the API documents zip explains what functions are there and how to call them. I have no idea why you used PEExplorer, are you using a device not covered by Slib.dll? Anyway, I suggest you forget about COM and try to load Slib.dll via ctypes http://docs.python.org/2/library/ctypes.html and call some functions documented in VC SDK.pdf and see what happens. The defines for return codes used in the documentation are here http://www.id-reader.com/Support/Sample_Codes/Visual_C_Plus_Plus/header_lib.rar in SlibErrDef.h and probably others... cheers Paul The SDK revolves around a .dll file that is described as a 'COM Object' but the text also implies that it can be accessed directly - If you don’t use the COM interface in your application and use the SDK files directly like in VC++ then you don’t need to install these files on the destination computer. If I look inside the .dll (thanks PEExplorer!), I see DllCanUnload, DllGetClassObject, DllRegisterServer and DllUnregisterServer in the 'Export' view. If I look at the 'Import' view, I can see the names of a bunch of .dll files and the names of the functions/methods I want to call. So I concluded that DllGetClassObject would be my friend. However, I've read various tutorials on using .dll and COM (ctypes, comtypes, and the Python documentation) and I've ended up more confused than when I started. I expected to be using COM but all the examples seem to revolve around automating excel or outlook. I'd be really grateful for some hints on what direction Ishould be headed and a pointer to a relevant tutorial. Simmo -- http://mail.python.org/mailman/listinfo/python-list
Re: Constructing JSON data structures from non-string key python dictionaries
Am 21.11.2012 17:04, schrieb hfo...@gmail.com: Thanks for your reply, but the javascript function expects option names to be unquoted, otherwise it won't work. Others have shown you how to solve this, but I would like to note that the function does NOT expect JSON but a simple javascript object literal. cheers Paul -- http://mail.python.org/mailman/listinfo/python-list
Re: Forking simplejson
Am 26.10.2011 19:34, schrieb Nathan Rice:
Since this happily went off to the wrong recipient the first time...
The python json module/simpljson are badly in need of an architecture
update. The fact that you can't override the encode method of
JSONEncoder and have it work reliably without monkey patching the pure
python encoder is a sign that something is horribly wrong.
+1
I wonder why the builtin json didn't implemented the __json__ hook. Now
you need to write encoders for possibly arbitrary (imported/third party)
objects Looks like it's not so hard to extend json.JSONEncoder to
look for __json__ though:
import json
from functools import partial
from types import MethodType
class Encoder(json.JSONEncoder):
... def default(self, obj):
fn = getattr(obj, '__json__', None)
... if fn and type(fn) == MethodType:
... return obj.__json__()
... return json.JSONEncoder.default(self, obj)
...
class T(object):
... def __json__(self):
... return 'foo'
...
t = T()
dumps = partial(json.dumps, cls=Encoder)
dumps(dict([(1,1), (2,2), ('test',t)]))
'{test: foo, 1: 1, 2: 2}'
cheers
Paul
[snip]
--
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Re: Need advice on Web / Database framework...
Hi, Am 03.09.2011 16:11, schrieb Benjamin Schollnick: Folks, I need some advice on a python web database framework to use...? Hardest question ever ;) I have handcrafted a sqllite3 python script, that is a basic web application, interfacing with a sqlite3 database... But I am concerned at the thought of handcrafting a administration interface, and so forth. If you are not familiar with the various pitfalls of web security I'd recomment a framework which has all the layers already integrated. Take a look at http://www.web2py.com, I think it's quite powerful and has good documentation. If you want to get your hands dirty you can compose your own framework cherrypy+sqlalchemy+cheetah might be a good combination. hth Paul -- http://mail.python.org/mailman/listinfo/python-list
Re: Installing WebDAV server
Hi, Am 30.08.2011 22:00, schrieb Fokke Nauta: Hi all, I am completely new to Python, but I'm confronted with a problem I can't solve. Welcome to python. This is my question: [snip] I installed Python 3.2.1 and extracted the packages PyWebDAV and PyXML. Now I have a working Python app and 2 directories called PyWebDAV-0.9.4.1 and PyXML-0.8.4. In the PyWebDAV README it says: Installation and setup of server can be as easy as follows: $ easy_install PyWebDAV $ davserver -D /tmp -n -J But of course it doesn't work like that. When I start up Python GUI I see the prompt instead of the $ prompt. But where do I place the two directories? And there is no easy_install script in the PyXML-0.8.4 directory, only a setup.py and ez_setup.py script. I guess the latter is the one to use. But how? You dont install from Python GUI, use normal cmd, navigate to the folder you downloaded PyXML and PyWebDAV and run python setup.py install (python.exe has to be in your PATH). Then you have to find the startup-script davserver. Find your python installation directory and look into Install dir/Tools/Scripts, in my computer this is E:\python27\Tools\Scripts. PyXML and PyWebDAV get installed in the site-packages folder i.e. E:\python27\Lib/site-packages. You might have to look for davserver there... hth Paul -- http://mail.python.org/mailman/listinfo/python-list
Re: Installing WebDAV server
Hi, answers below... Am 31.08.2011 14:18, schrieb Fokke Nauta: Paul Köllep...@subsignal.org wrote in message news:mailman.595.1314780791.27778.python-l...@python.org... Hi, Am 30.08.2011 22:00, schrieb Fokke Nauta: Hi all, I am completely new to Python, but I'm confronted with a problem I can't solve. Welcome to python. This is my question: [snip] I installed Python 3.2.1 and extracted the packages PyWebDAV and PyXML. Now I have a working Python app and 2 directories called PyWebDAV-0.9.4.1 and PyXML-0.8.4. In the PyWebDAV README it says: Installation and setup of server can be as easy as follows: $ easy_install PyWebDAV $ davserver -D /tmp -n -J But of course it doesn't work like that. When I start up Python GUI I see the prompt instead of the $ prompt. But where do I place the two directories? And there is no easy_install script in the PyXML-0.8.4 directory, only a setup.py and ez_setup.py script. I guess the latter is the one to use. But how? You dont install from Python GUI, use normal cmd, navigate to the folder you downloaded PyXML and PyWebDAV and run python setup.py install (python.exe has to be in your PATH). Then you have to find the startup-script davserver. Find your python installation directory and look intoInstall dir/Tools/Scripts, in my computer this is E:\python27\Tools\Scripts. PyXML and PyWebDAV get installed in the site-packages folder i.e. E:\python27\Lib/site-packages. You might have to look for davserver there... Thanks, Paul. I ran python setup.py install in both the PyXML and PyWebDAV directories. A lot of things happened and are added into those directories and I guess it will be OK. Next step, the startup-script davserver. There is no script as such, also not in \python27\tools\scripts. I found 2 similar scripts: 1. server.py in D:\Python27\WebDAV\PyWebDAV\DAVServer 2. WebDAVServer.py in D:\Python27\WebDAV\PyWebDAV\DAV Which one is the one to use? Your install locations look odd, but it might work nevertheless. The server is in DAVServer\server.py, you can look at the file and you will see: if __name__ == '__main__': run() at the bottom. This is the entry point of a python script if called from the command line. My install looks a bit different but I can start the server as follows: python.exe E:\Python27\Lib\site-packages\pywebdav-0.9.4.1-py2.7.egg\DAVServer\server.py -D c:\home -n WARNING:pywebdav:Authentication disabled! Listening on localhost (8008) I also configured config.ini in D:\Python27\WebDAV\PyWebDAV\DAVServer I would use a config file outside the program directory and use the -c or --config switch, run server.py without arguments to see possible startup options. In this file it says: # Auth Database Table, Must exists in database prior to firstrun dbtable=webDav # Create User Database Table and Insert system user I created in MySQL a database called webDav. I can create a table called User, but how many fields? Don't know if that's documented somewhere but you can just look at the code in mysqlauth.py in the same directory as server.py. Seems it needs three columns, (Userstring,Passstring,can_write0|1) but I haven't tried. cheers Paul -- http://mail.python.org/mailman/listinfo/python-list
Re: Methods on file-like objects can only used once on one object?
Am 23.08.2011 16:21, schrieb Yingjie Lin: Hi Python users, [snip] There are quite a few methods for file-like objects that can only be used once on one object. If I prefer to use some of these methods on one object, one after another, like: f.readlines() f.read() ... What should I do? Thank you. use f.seek(0) between calls. The python documentation will educate you about the details. hth Paul -- http://mail.python.org/mailman/listinfo/python-list
Re: Order of addresses returned by socket.gethostbyname_ex()
Am 22.08.2011 13:37, schrieb Roy Smith: In article c4163eeb-c306-49d1-9337-0eb9f47df...@s12g2000yqm.googlegroups.com, Tomas Lidéntomas.liden.pri...@gmail.com wrote: A cross-platform deterministic order would be excellent for us. A cross-platform deterministic X would be excellent is a true statement for almost any value of X. Many people have wasted much of their lives trying to achieve that goal, for various Xs. So true..., QOTW +1 -- http://mail.python.org/mailman/listinfo/python-list
Re: Please code review.
Am 02.08.2011 13:45, schrieb Karim:
Hello,
I need a generator to create the cellname in a excell (using pyuno)
document to assign value to
the correct cell. The following code does this but do you have some
optimizations
on it, for instance to get the alphabetic chars instead of hard-coding it.
you can use:
import string
cellnames = string.ascii_uppercase
not sure why you need the .replace().split() stuff...
def _xrange_cellnames(rows, cols):
cellnames = string.ascii_uppercase
for row in xrange(1, rows+1):
for char in cellnames[:rows]:
yield char + str(row)
cheers
Paul
Cheers
karim
Python 2.7.1+ (r271:86832, Apr 11 2011, 18:13:53)
[GCC 4.5.2] on linux2
Type help, copyright, credits or license for more information.
def _xrange_cellnames(rows, cols):
... Internal iterator function to compute excell table cellnames.
... cellnames = 'ABCDEFGHIJKLMNOPQRSTUVWXYZ'
... for row in xrange(1, rows+1):
... for char in cellnames.replace('', ' ').split()[:cols]:
... yield char + str(row)
...
list( _xrange_cellnames(rows=3,cols=4))
['A1', 'B1', 'C1', 'D1', 'A2', 'B2', 'C2', 'D2', 'A3', 'B3', 'C3', 'D3']
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Re: How to build an application in Django which will handle Multiple servers accross network
Hi, Am 29.04.2011 12:01, schrieb Adam Tauno Williams: On Thu, 2011-04-28 at 23:47 -0700, Anurag (anu) Agarwal wrote: Hi All, I want to build an application for one of my client which has following features 1. Client has some driver software which can be installed on Windows and Linux based systems. This driver software is fetching some operating system details using kernel level programming. This is commonly called an agent. You might not want do write your own because it is hard to do correctly and takes a lot of time. I'd suggest you search for something like sigar (library) or collectd and check out what they can offer in terms of output formats. 2. Now a new web based application is required to moniter these servers remotly. This application will talk to these servers and get the data (not sure how data will be fetched from driver software) then show it on UI. Perhaps via WMI? Yes, best option. Modern windows versions have WinRM which is basically WMI over http (wmi being an implementation of CIM over DCOM, but I digress...) 3. The web based application will be used internally in the network to moniter servers in that network only. You mean like OpenNMS or ZenOSS? 4. Web based application will be a real time application with a Database. Like OpenNMS or ZenOSS? How can they be realtime if they generate static images? 5. Technology I am thingking for web based application is Django and Python as this web application can also be installed on Windows or Linux based OS. If you want real-time monitoring you *must* build a service; a 'web app' can *not* do that. Do you mean an agent? 6. Also please suggest which third party tool for chatrs and graphs I should use with Django (open source + paid) ZenOSS and OpenNMS do graphs using RRD. I know this is the standard but IMO it's totally backward these days. Correlating or selecting/deselecting certain values is painful (you have to write a graph def). With canvas and modern JS libs like raphael there are better ways to do this. Just look at google analytics. On the other hand, RRD (the database) is great, I just never got the python bindings for rrd_fetch to reliably fetch the values I needed (you can't tell it to stop normalizing ) It looks like PCP (http://oss.sgi.com/projects/pcp/features.html) will gain a JSON interface shortly. That would be awesome because PCP is developed by real engineers and has a proper architecture and is NOT a CPU sucking monstrosity of PERL-line-noise + a few hacked-together PHP frontends. just my 2cents Paul -- http://mail.python.org/mailman/listinfo/python-list
Re: [Beginer Question] I heard about python needing somesort of_VariableName_ boiler plate?
Its the entry point if the script is executed directly. This message was sent from my 7 years old Dell D800 (without cables) Am 01.11.2010 19:18, schrieb brad...@hotmail.com: Sorry that is what I mean. What is it for? Sent wirelessly from my BlackBerry. -Original Message- From: MRABpyt...@mrabarnett.plus.com Sender: python-list-bounces+bradenf=hotmail@python.org Date: Mon, 01 Nov 2010 17:33:22 To:python-list@python.org Reply-To: python-list@python.org Subject: Re: [Beginer Question] I heard about python needing some sortof_VariableName_ boiler plate? On 01/11/2010 04:51, Ben Finney wrote: brad...@hotmail.com writes: Sorry, to clarify I heard that when you declare a variable in python you have to use some sort of standard boiler plate _variable_ however this has not been my experience using IDLE so is this even true? I don't know what “some sort of boiler plate _variable_” might mean. Can you point to someone's actual message saying this, so we can see what they might be talking about? Perhaps the OP means: if __name__ == __main__: ... although the declare a variable bit has me puzzled. -- http://mail.python.org/mailman/listinfo/python-list
Re: please help explain this result
Am 17.10.2010 13:48, schrieb Steven D'Aprano:
On Sun, 17 Oct 2010 03:58:21 -0700, Yingjie Lan wrote:
Hi,
I played with an example related to namespaces/scoping. The result is a
little confusing:
[snip example of UnboundLocalError]
Python's scoping rules are such that if you assign to a variable inside a
function, it is treated as a local. In your function, you do this:
def f():
a = a + 1
Since a is treated as a local, when you enter the function the local a is
unbound -- it does not have a value. So the right hand side fails, since
local a does not exist, and you get an UnboundLocalError. You are trying
to get the value of local a when it doesn't have a value.
Oh really? Can you explain the following?
a = {}
def foo():
... a['a'] = 'lowercase a'
... print a.keys()
...
foo()
['a']
a
{'a': 'lowercase a'}
def bar():
... a['b'] = a['a'].replace('a', 'b')
...
bar()
a
{'a': 'lowercase a', 'b': 'lowercbse b'}
cheers
Paul
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Re: please help explain this result
Am 17.10.2010 19:51, schrieb TomF:
On 2010-10-17 10:21:36 -0700, Paul Kölle said:
Am 17.10.2010 13:48, schrieb Steven D'Aprano:
On Sun, 17 Oct 2010 03:58:21 -0700, Yingjie Lan wrote:
Hi,
I played with an example related to namespaces/scoping. The result is a
little confusing:
[snip example of UnboundLocalError]
Python's scoping rules are such that if you assign to a variable
inside a
function, it is treated as a local. In your function, you do this:
def f():
a = a + 1
Since a is treated as a local, when you enter the function the local
a is
unbound -- it does not have a value. So the right hand side fails, since
local a does not exist, and you get an UnboundLocalError. You are trying
to get the value of local a when it doesn't have a value.
Steven's explanation is correct. In your example below you're altering
portions of a global data structure, not reassigning a global variable.
Put another way, there is a significant difference between:
a = 7
and:
a['x'] = 7
Only the first reassigns a global variable.
Thanks Tom and Dennis.
This will teach me (hopefully) to pay attention to details next time and
I think I learned something too. I always thought the rules about
changing global objects where inconsistent because it works for
mutables... Turns out it's all fine since assignment doesn't work for
mutables too and assignment just happens to be the only way to change
immutables ;)
cheers
Paul
-Tom
Oh really? Can you explain the following?
a = {}
def foo():
... a['a'] = 'lowercase a'
... print a.keys()
...
foo()
['a']
a
{'a': 'lowercase a'}
def bar():
... a['b'] = a['a'].replace('a', 'b')
...
bar()
a
{'a': 'lowercase a', 'b': 'lowercbse b'}
cheers
Paul
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Re: Windows - select.select, timeout and KeyboardInterrupt
Am 09.05.2010 11:59, schrieb Lawrence D'Oliveiro: In messagemailman.2769.1273327083.23598.python-l...@python.org, exar...@twistedmatrix.com wrote: On 07:48 am, l...@geek-central.gen.new_zealand wrote: In messagemailman.2760.1273288730.23598.python-l...@python.org, exar...@twistedmatrix.com wrote: This is a good example of why it's a bad idea to use select on Windows. Instead, use WaitForMultipleObjects. How are you supposed to write portable code, then? With WaitForMultipleObjects on Windows, epoll on Linux, kqueue on BSD, event completion on Solaris, etc... Sound like more work than using select() everywhere? Yea, a bit. But not once you abstract it away from your actual application code. After all, it's not like these *do* different things. They all do the same thing (basically) - differently. Do you understand what “portable” means? Yes. For me it means run as best as possible on all platforms I care about. It does *not* mean force one method from *one* platform upon all platforms for purely ideological reasons (like GTK being too stupid to tell the difference between %HOMEPATH% and %APPDATA%). cheers Paul -- http://mail.python.org/mailman/listinfo/python-list
Re: Django as exemplary design
Am 07.05.2010 04:48, schrieb TomF: On 2010-05-06 18:20:02 -0700, Trent Nelson said: I'm interested in improving my python design by studying a large, well-designed codebase. I'll tell you one of the best ways to improve your Python code: attend one of Raymond Hettinger's Code Clinic workshops at a Python conference and put some up of your work up on the projector for 20+ developers to rip apart, line by line ;-) You'll pick up more in 30 minutes than you ever thought possible. I don't doubt it. But I'm not really interested in line (micro) level code issues at the moment. Not that my code couldn't stand being improved, but I'm more interested in seeing how medium/large OO python systems are designed. If I could get this from a book I would, but I suspect I need to study real code. Then trac might be a good candidate, start here http://trac.edgewall.org/wiki/TracDev/ComponentArchitecture then read http://trac.edgewall.org/browser/trunk/trac/core.py#latest there is one rather dubious hack in the implementation of implements() but I like the conceptual simplicity. cheers Paul -- http://mail.python.org/mailman/listinfo/python-list
Re: Accessing an instance of a class from within instance of another class
Am 30.04.2010 13:05, schrieb Stefan Krastanov: Hello all, [snipp] Here is the problem: I have a class (call it Data) that has a number of NumPy arrays and some methods that get useful information from the arrays (math stuff). I have two other classes (called Viewer1 and Viewer2) (they are subclasses of QAbstractTableModel but that's not important). I am working in my code with one instance of each class. Viewer1 and Viewer2 must be able to call methods from the Data instance, but as the instance of Data is constantly updated, I cannot just copy it. Why do you think the data is copied? Both viewers will hold a reference to the same data object: Type help, copyright, credits or license for more information. class d(object): ... a = 1 ... b = 2 ... c = 3 ... d1 = d() d1.a 1 class view1(object): ... def __init__(self, data): ... self.data = data ... def data(self): ... return self.data ... class view2(object): ... def __init__(self, data): ... self.data = data ... def data(self): ... return self.data ... v1 = view1(d1) v2 = view2(d1) v2.data.b 2 v2.data.b = 4 v2.data.b 4 v1.data.b 4 hth Paul -- http://mail.python.org/mailman/listinfo/python-list
Re: plugin / intra process communication system
Am 15.02.2010 23:12, schrieb Florian Ludwig: On Sun, 2010-02-14 at 18:47 +0100, Diez B. Roggisch wrote: [...] And then of course, this is not really needed. In Python, behavior counts, not type-information. So you can get away without any explicit declared interface. You might chose to not do that, for aestetic reasons, or better documentation. But you aren't forced. Actually some plugin-systems in python do force you and they check if your implementation comply with the interface. Which is a good thing IMO ;) Here is one solution I came up with. [...] Can you post working code? It's not clear what pbus is and how it works. cheers Paul What do you think? Any obvious pitfalls (besides reinventing something)? Please keep in mind that syntax/api is not done or anything its just an concept presentation. Thanks, Florian -- http://mail.python.org/mailman/listinfo/python-list
Re: plugin / intra process communication system
Am 13.02.2010 10:50, schrieb Florian Ludwig: Hi, I'm looking for a module/plugin/intra-process-communication/hook system for python. Maybe someone here could point me to some project I missed or might have some good ideas if I end up implementing it myself. Most systems I have found are one to many communications but I would like many to many, to clarify what I mean an *example* use-case: Lets say you program a wiki and like to allow different kind of authentications. So you create two plugins (for example one for OpenID and one for Shibboleth). Some time later you feel like reinventing the wheel again and you program a blog. Again you like to allow different ways of authentication and you already wrote plugins for exactly the same for your wiki, right? With most systems now some trouble begins - the blog software would need to have the interface/extention-points/however-you-name-it that the wiki software defined. The plugins you wrote probably import them from the wiki module directly which means your blog would depend on the wiki. (?!) So where to put the interface/[...] definition that is imported by those plugins? Create a package/module just containing the interface? This really get troublesome if different people wrote the wiki, the blog and another third one a plugin. If you are talking about code sharing you can move the common code out of your applications in a seperate namespace. If you follow the model trac is using you would install a module/package/egg with the basic functionality of the pluginsystem (i.e. what's in core.py and env.py + logging and whatever you think is necessary). All shared code like your auth-plugins would go in a common plugin directory to which you can refer via PYTHONPATH. Another common technique is chaining of WSGI middleware..., check out pythonpaste.org. Then there is SOA where functionality is shared via RPC/webservices and wsdl/uddi. But my feeling is this is mostly used in Enterprise applications and is best used in Java/.NET where you already have libraries doing all the XML stuff. hth Paul -- http://mail.python.org/mailman/listinfo/python-list
Re: Trying to run a sudo command from script
Am 01.01.2010 23:55, schrieb Kent Tenney:
Howdy,
Hi Kent,
A script running as a regular user sometimes wants
to run sudo commands.
It gets the password with getpass.
pw = getpass.getpass()
I've fiddled a bunch with stuff like
proc = subprocess.Popen('sudo touch /etc/foo'.split(), stdin=subprocess.PIPE)
proc.communicate(input=pw)
If you don't use shell=True you have to provide the full path to
commands (and split command and parameters as you do). So eather of this
works for me:
p = Popen('/usr/bin/sudo /usr/bin/touch /tmp/foo.txt'.split(),
stdin=PIPE, stdout=PIPE)
p = Popen('/usr/bin/sudo /usr/bin/touch /tmp/foo2.txt', stdin=PIPE,
stdout=PIPE, shell=True)
The bad news is: It this gives me a password promt inside the
interactive interpreter. Seems you can't catch stdout this way.
hth
Paul
getting assorted errors with all variations I try.
Googling says use pexpect, but I'd prefer a stdlib solution.
Any help appreciated.
Thanks,
Kent
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Re: Egg problem (~/.python-eggs)
Mike Orr wrote:
[... snipp ...]
Can I make it use a different eggs directory? Any other idea how to
install a program using eggs on a server?
I had a similar issue with tracd on gentoo. My solution was setting
PYTHON_EGG_CACHE=/tmp/.egg_cache in /etc/conf.d/tracd and exporting that
var in /etc/init.d/tracd before calling start-stop-daemon, e.g.
export PYTHON_EGG_CACHE=${PYTHON_EGG_CACHE}
start-stop-daemon --start
cheers
Paul
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Re: Using Python for my web site
Cliff Wells wrote: For myself, I handle user-installation of TurboGears pretty much like I do all user-installed Python packages: using setuptools. Any user who uses easy_install or 'python setup.py install' gets their packages automatically installed into a subdirectory of their home directory and that takes precedence over the system installed packages. Works like a charm. May I ask how you handle clashes with packages already installed in site-packages? Once I tried something like ~/lib/python and set up distutils accordingly, easy_install wouldn't work if the package was installed system-wide... thanks Paul -- http://mail.python.org/mailman/listinfo/python-list
Re: Type signature
Marc 'BlackJack' Rintsch wrote: In [EMAIL PROTECTED], Yacao Wang wrote: However, type signatures are not only a kind of information provided for the compiler, but also for the programmer, or more important, for the programmer. Without it, we have to infer the return type or required agument types of a function, and this can't be done without seeing the implementation of it, That's what documentation is meant for. If you are forced to look at the implementation, the documentation is bad. I think the OP refers to reading the *code*, the documentation might not exist (yet). Sometimes I feel python is easier to write than to read and missing argument type declarations (just for documentation purposes) are IMHO one reason. Another are missing (optional) argument type checks at runtime. Something like WrongArgumentType exceptions instead of rather unspecific AttributeError from deep inside the code would be very convenient. Yes docstrings are nice but sometimes a simple: foo(int:param1, string:param2) is way better than: foo(param1, param2): @type param1: integer @type parame2: string cheers Paul -- http://mail.python.org/mailman/listinfo/python-list
Re: SQLObject connection/transaction blowing up
[EMAIL PROTECTED] wrote: I'm trying to connect to a mysql database, with autoCommit and caching off, and I'm trying to create a transaction. Why does this blow up? As the traceback is telling you, your connectionString is missing the actual values. Not sure about the cache parameter but: connectionString = 'mysql://[EMAIL PROTECTED]/mc_image_library_dev?autoCommit=1' should work. cheers Paul from sqlobject import * connectionString = 'mysql://[EMAIL PROTECTED]/mc_image_library_dev?cache=autoCommit=' [snipp] conn.autocommit(self.autoCommit) TypeError: an integer is required -- http://mail.python.org/mailman/listinfo/python-list
Re: unittest setup
Diez B. Roggisch wrote:
paul kölle wrote:
hi all,
I noticed that setUp() and tearDown() is run before and after *earch*
test* method in my TestCase subclasses. I'd like to run them *once* for
each TestCase subclass. How do I do that.
Create a global/test instance flag.
I'm not sure if I understood what you mean, I tried:
setup = 'down'
class BaseTest(unittest.TestCase):
def setUp(self):
global setup
if setup == 'up':
print 'Not running setUp() again...'
return
...
all setup work goes here.
...
setup = 'up'
This didn't work, (tried to reset the flag in the last test* method to
'down', no dice)
and:
class BaseTest(unittest.TestCase):
def __init__(self, ...):
unittest.TestCase.__init__(self, ...)
self.setup = 'down'
def setUp(self):
if self.setup == 'up':
return
dowork
self.setup = 'up'
Failed also, I'm not sure why, __init__ was called way too often and
self.setup was always reset to 'down'. I finally gave up and created my
own method which I call in *every* test* method which is ugly, leads to
longer runtime and code duplication.
But at least it encouraged me to read the unittest docs more carefully.
Now I seem to understand that:
TestSuite.addTest(TestCaseSubclass('testSomething'))
TestSuite.addTest(TestCaseSubclass('testSomethingOther'))
will create two instances of TestCaseSubclass, so there is no way that
'testSomethingOther' will ever see what 'testSomething' might have
created if all work is done with instance data right? Initially I
thought it goes like: run setUp(), run all test* methods, run
tearDown() and that is what the unittest docs call a fixture
cite python 2.3 docs for unittest
A test fixture represents the preparation needed to perform one or more
tests, and any associate cleanup actions.
/cite
but further down:
cite python 2.3 docs for unittest
Each instance of the TestCase will only be used to run a single test
method, so a new fixture is created for each test.
/cite
It seems to me my case is not that exotic, I thought it would be quite
natural to write the boilerplate stuff in setUp() and build on that to
step through the applications state with test* methods each building on
top of each other. Is that the wrong approach? Are there other
frameworks supporting such a style?
thanks
Paul
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Re: Python Digest authentication against MS MapPoint
[EMAIL PROTECTED] wrote: [problem with digest auth] sorry for giving such a generic advice, but I'd capture the headers of the C# app and compare with the urllib version line by line. Try to reproduce the exact header with python (except the response and cnonce of course). Maybe IIS has its own version of rfc2617. hth Paul -- http://mail.python.org/mailman/listinfo/python-list
