Re: [Tutor] exit handler for C extension module
Shuying Wang, 18.01.2010 03:13: > What would be an atexit equivalent for a C extension module? When my > extension module is unloaded, I would like some clean up functions to > be called from an external c library. I've had a look at the C > extension guide but I can't find anything like that, I'm not aware of anything special here. Just use the "atexit" module itself and register a Python function. At least, that's what we do in Cython for any module level cleanup. You may also consider adding some hints on what you want to use it for, maybe there is some support for your actual use case. Stefan ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] Book for Python and XML
Григор, 15.01.2010 08:28: > Someone to have good E-book for python and XMl The existing books are rather old. You might find these interesting, though: http://effbot.org/zone/element.htm http://codespeak.net/lxml/tutorial.html http://www.nmt.edu/tcc/help/pubs/pylxml Stefan ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] Confirmation about __init__()
On 01/17/10 16:42, Robert wrote: > I have read quite a bit in the past 2 months, ( I have also looked at codes) > At this point, I think I understand well what __init__() is and does - > But, I have yet to see this *specifically* spelled out about the the > __init__ method for a Class; > > It is OPTIONAL, correct ? > > if I have NO start values/variables to set, no Base Class __init__ to > call --- the __init__ method is NOT required, correct ? No, __init__ is always required for new-style classes; however due to object inheritance (all new-style classes inherits from `object`), all new-style classes inherits the do-nothing __init__ from `object`. Essentially, it means __init__ can be omitted if it does the same as the super class' __init__. More generally, a method (e.g. MyClass.__init__) that does not override the superclass' method (e.g. MySuperClass.__init__) will use the superclass' definition of the method (i.e. when MyClass inherits from MySuperClass, and __init__ is not overrided in MyClass, MyClass.__init__ == MySuperClass.__init__). ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: http://mail.python.org/mailman/listinfo/tutor
[Tutor] exit handler for C extension module
Hi, What would be an atexit equivalent for a C extension module? When my extension module is unloaded, I would like some clean up functions to be called from an external c library. I've had a look at the C extension guide but I can't find anything like that, Thanks in advance, .S ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] adding more text to a file
"Magnus Kriel" wrote It might be that when you create a file for the first time with 'a', that it will through an exception. So you will have to try with 'w', and if there is an exception, you know the file does not exist and you will have to create the file for the first time with 'w'. That should not happen. If there is no file 'a' will act like 'w' Alan G. ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] adding more text to a file
"Shizuha Aki" wrote
i need it to be able to add more entries instead of just one.
my code is like this:
while True:
name = raw_input("what is the name ")
age = raw_input("what is the age ")
out_file = open("persons.txt", "w")
It would work if you moved the open() call outside the loop
so the file is only opened once. Every time you open the file
you create a new file on top of the old one. You need to
move the close outside the loop too of course. That way
you don't need append mode unless you want to run the
program multiple times to keep adding data.
out_file.write("name: ")
out_file.write(name)
out_file.write("\n")
You should join the strings together and write a full line out at once.
It will be more efficient and possibly more resilient too.
--
Alan Gauld
Author of the Learn to Program web site
http://www.alan-g.me.uk/
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Re: [Tutor] Subclassing object
"Robert" wrote I have been wondering about this "New-style Class" subject along this line: so, *theoretically speaking*, in EXISTING, pre-P3K code, if one changes everywhere where it's coded "class someClass()" to "class someClass(object)", it should not break the programs, right ? More correctly replacing old style class SomeClass: with new style class SomeClass(object): should not break anything. You cannot of course reliably go the other way! Alan G ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] smtp project
On So, 2010-01-17 at 15:45 -0500, Kirk Z Bailey wrote: > I am writing a script that will send an email message. This will > run in a windows XP box. The box does not have a smtp server, so > the script must crete not merely a smtp client to talk to a MTA, > it must BE one for the duration of sending the message- then shut > off, we don't need no bloody op0en relays here! Twisted is the obvious choice for a server daemon, but it should be good enough for what you do, too. What you need isn't a "SMTP server", it's a "SMTP sender", which is more like a client than a server in the usual model. As you don't want it to run as a daemon, first consider how you want it to behave if the server (SMTP receiver, the destination or a server that is willing to relay the message) is not responding or responds with an error. A message queue (in terms of days not seconds) is out of the question for a fire-and-forget service like the one you want, so you probably want the transfer synchronously, i.e. somewhere between receiving the user's input (or whatever triggers the script) and the output (or the end of the lifetime of whatever script was triggered). If you're dealing with real users, though, this can mean an unexpected pause of several seconds, depending on how long the delivery takes (or how long it takes to notice it's not going anywhere). This is bad if the user isn't expecting it (zero progress can be interpreted as a freeze). Anyway. Take a look at Twisted or other libraries for SMTP senders or "clients". Actual SMTP servers are mostly concerned with accepting mail via SMTP and doing something with them (if they are capable of relaying, they can also act as SMTP senders, otherwise they probably just deliver the mail locally or forward them to a local message queue for a separate SMTP sender). Hope that helped a bit, Alan Plum ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] smtp project
Kent Johnson wrote: > On Sun, Jan 17, 2010 at 3:45 PM, Kirk Z Bailey > wrote: >> I am writing a script that will send an email message. This will run in a >> windows XP box. The box does not have a smtp server, so the script must >> crete not merely a smtp client to talk to a MTA, it must BE one for the >> duration of sending the message- then shut off, we don't need no bloody >> op0en relays here! > > Is there no SMTP server available on another machine? Can you send > email from a regular email client (e.g. Thunderbird)? Unless I'm missing something, you're probably overly complicating your solution. You don't need to open a local relay just to *send* a message from the same script. Your script can connect to whatever upstream SMTP server your organization uses and send mail to it directly. >> I am RTFM and having some heavy sledding, can I get an Elmer on this? > > An Elmer? Old Amateur Radio term. An "Elmer" is someone who mentors new people and shows them the ropes. Which is essentially what the list is for. ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] smtp project
On Sun, Jan 17, 2010 at 3:45 PM, Kirk Z Bailey wrote: > I am writing a script that will send an email message. This will run in a > windows XP box. The box does not have a smtp server, so the script must > crete not merely a smtp client to talk to a MTA, it must BE one for the > duration of sending the message- then shut off, we don't need no bloody > op0en relays here! Is there no SMTP server available on another machine? Can you send email from a regular email client (e.g. Thunderbird)? > I am RTFM and having some heavy sledding, can I get an Elmer on this? An Elmer? Kent ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] adding more text to a file
> while True:
> name = raw_input("what is the name ")
> age = raw_input("what is the age ")
>
> out_file = open("persons.txt", "w")
> out_file.write("name: ")
> out_file.write(name)
> out_file.write("\n")
> out_file.write("age: ")
> out_file.write(age)
> out_file.write("\n")
> out_file.write("\n")
> out_file.close
while everyone is helping you with your original inquiry, i'm going to
inject some "Pythonic" style guidelines here.
1. i would strongly suggest calling the close() method instead of
merely providing the object. in other words, change your last line to
"out_file.close()" so you execute it. otherwise your file contents are
not guaranteed.
2. try to minimize the total number of calls to write() to make things
run faster. for example, your code only really needs one call:
out_file.write("name: %s\nage: %s\n\n" % (name, age))
the reason why it's faster is because you pay a little bit of overhead
with every function call you make. of course, since your example
requires human input each time, it doesn't make as much of a
difference in this example, but this is mostly a general suggestion.
hope this helps!
-- wesley
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
"Core Python Programming", Prentice Hall, (c)2007,2001
"Python Fundamentals", Prentice Hall, (c)2009
http://corepython.com
wesley.j.chun :: wescpy-at-gmail.com
python training and technical consulting
cyberweb.consulting : silicon valley, ca
http://cyberwebconsulting.com
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Re: [Tutor] what is dynamic about "dynamic name resolution" ?
On Sun, Jan 17, 2010 at 12:10 PM, Robert wrote: > In the Python tutorial (highlighted here http://awurl.com/N1XvzIo2Q) > > What exactly is "dynamic name resolution" ? specifically what is > "dynamic" about it ? what this means is that as your code is executing and the interpreter encounters an identifier/variable, it "dynamically" looks up the variable at that point -- it checks at that point to see if it's a local variable; if not, global; finally it checks if it's a built-in. to rephrase: this check is *not* done during compile time (static); instead, it is done during runtime (dynamic). if it were static, it would've already been checked *before* your code ever started running. hope this helps! -- wesley - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - "Core Python Programming", Prentice Hall, (c)2007,2001 "Python Fundamentals", Prentice Hall, (c)2009 http://corepython.com wesley.j.chun :: wescpy-at-gmail.com python training and technical consulting cyberweb.consulting : silicon valley, ca http://cyberwebconsulting.com ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: http://mail.python.org/mailman/listinfo/tutor
[Tutor] smtp project
I am writing a script that will send an email message. This will run in a windows XP box. The box does not have a smtp server, so the script must crete not merely a smtp client to talk to a MTA, it must BE one for the duration of sending the message- then shut off, we don't need no bloody op0en relays here! I am RTFM and having some heavy sledding, can I get an Elmer on this? -- end Very Truly yours, - Kirk Bailey, Largo Florida kniht +-+ | BOX | +-+ think ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: http://mail.python.org/mailman/listinfo/tutor
[Tutor] what is dynamic about "dynamic name resolution" ?
In the Python tutorial (highlighted here http://awurl.com/N1XvzIo2Q) What exactly is "dynamic name resolution" ? specifically what is "dynamic" about it ? thanks ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] adding more text to a file
Thanx, you are correct. And now I know that 'a' will create a file as well. Magnus On Sun, Jan 17, 2010 at 10:34 AM, Steve Willoughby wrote: > Magnus Kriel wrote: > > It might be that when you create a file for the first time with 'a', > > that it will through an exception. So you will have to try with 'w', and > > if there is an exception, you know the file does not exist and you will > > have to create the file for the first time with 'w'. > > That's a little confusing, I think. I think you meant "try with 'a' and > if there is an exception ... create ... with 'w'" but that shouldn't be > necessary anyway. Opening a file with 'a' will append to an existing > file, or create a new file if one doesn't exist already. > > ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] adding more text to a file
Magnus Kriel wrote: > It might be that when you create a file for the first time with 'a', > that it will through an exception. So you will have to try with 'w', and > if there is an exception, you know the file does not exist and you will > have to create the file for the first time with 'w'. That's a little confusing, I think. I think you meant "try with 'a' and if there is an exception ... create ... with 'w'" but that shouldn't be necessary anyway. Opening a file with 'a' will append to an existing file, or create a new file if one doesn't exist already. ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] Subclassing object
On Sun, Jan 17, 2010 at 12:47 PM, Robert wrote: > On Sun, Jan 17, 2010 at 11:25 AM, Alan Gauld > wrote: >> In older versions of Python it made a difference whether you used object >> or not. Using object gave you a "new style" class which has several extra >> features, without you got an "old style class" without the features. I have been wondering about this "New-style Class" subject along this line: so, *theoretically speaking*, in EXISTING, pre-P3K code, if one changes everywhere where it's coded "class someClass()" to "class someClass(object)", it should not break the programs, right ? ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] adding more text to a file
Hi,
It is the way you open the text file in the beginning.
This is from the python manual:
open() returns a file object, and is most commonly used with two arguments:
"open(filename, mode)".
>>> f=open('/tmp/workfile', 'w')
>>> print f
The first argument is a string containing the filename. The second argument
is another string containing a few characters describing the way in which
the file will be used. mode can be 'r' when the file will only be
read, 'w'for only writing (an existing file with the same name will be
erased), and
'a' opens the file for appending; any data written to the file is
automatically added to the end. 'r+' opens the file for both reading and
writing. The mode argument is optional; 'r' will be assumed if it's omitted.
You should use 'a' and not 'w'.
It might be that when you create a file for the first time with 'a', that it
will through an exception. So you will have to try with 'w', and if there is
an exception, you know the file does not exist and you will have to create
the file for the first time with 'w'.
Hope it helps.
Buy the way, why don't you try sqlite for your database structure? sqlite is
still a single file, not like MySQL. You get a pysqilte at :
http://pypi.python.org/pypi/pysqlite/
Magnus Kriel
The 'W' means write. An 'A' means append
On Sun, Jan 17, 2010 at 9:40 AM, Shizuha Aki wrote:
> Hi,
>
> I am new to python, and i am trying to make a program that makes like a txt
> file database. so i have my whole program in a while True loop, it asks for
> information about the person and then writes the information about the
> person to a txt file, but i need it to be able to add more entries instead
> of just one.
>
> my code is like this:
>
> while True:
>name = raw_input("what is the name ")
>age = raw_input("what is the age ")
>
>out_file = open("persons.txt", "w")
>out_file.write("name: ")
>out_file.write(name)
>out_file.write("\n")
>out_file.write("age: ")
>out_file.write(age)
>out_file.write("\n")
>out_file.write("\n")
>out_file.close
>
> now i want to add like say 5 persons to the txt file, but whenever i enter
> a new person it just overwrites the previous, im sure its because of the "w"
> but how exactly do i need to change my code to add more text instead of
> overwriting?
>
>
> ___
> Tutor maillist - Tutor@python.org
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>
>
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Re: [Tutor] adding more text to a file
On Sun, Jan 17, 2010 at 6:40 PM, Shizuha Aki wrote:
> Hi,
>
> I am new to python, and i am trying to make a program that makes like a txt
> file database. so i have my whole program in a while True loop, it asks for
> information about the person and then writes the information about the
> person to a txt file, but i need it to be able to add more entries instead
> of just one.
>
> my code is like this:
>
> while True:
> name = raw_input("what is the name ")
> age = raw_input("what is the age ")
>
> out_file = open("persons.txt", "w")
> out_file.write("name: ")
> out_file.write(name)
> out_file.write("\n")
> out_file.write("age: ")
> out_file.write(age)
> out_file.write("\n")
> out_file.write("\n")
> out_file.close
>
> now i want to add like say 5 persons to the txt file, but whenever i enter a
> new person it just overwrites the previous, im sure its because of the "w"
> but how exactly do i need to change my code to add more text instead of
> overwriting?
>
you should check the python documentation for the 'open' function.
help() is your friend, works on any interactive session. On linux, you
could also check out the pydoc program. Or you could check the website
docs.python.org.
Hugo
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[Tutor] adding more text to a file
Hi,
I am new to python, and i am trying to make a program that makes like a txt
file database. so i have my whole program in a while True loop, it asks for
information about the person and then writes the information about the person
to a txt file, but i need it to be able to add more entries instead of just one.
my code is like this:
while True:
name = raw_input("what is the name ")
age = raw_input("what is the age ")
out_file = open("persons.txt", "w")
out_file.write("name: ")
out_file.write(name)
out_file.write("\n")
out_file.write("age: ")
out_file.write(age)
out_file.write("\n")
out_file.write("\n")
out_file.close
now i want to add like say 5 persons to the txt file, but whenever i enter a
new person it just overwrites the previous, im sure its because of the "w" but
how exactly do i need to change my code to add more text instead of overwriting?
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Re: [Tutor] Subclassing object
"Timo Vanwynsberghe" wrote I read that it is advised to subclass object. Is it really necessary? I mean, everything works, why should I add it to my code? In older versions of Python it made a difference whether you used object or not. Using object gave you a "new style" class which has several extra features, without you got an "old style class" without the features. In Python v3 you only get new style classes and I think you can omit the object without detriment. For comparison here are Python v2.5 definitions class New(object): pass ... dir(New) ['__class__', '__delattr__', '__dict__', '__doc__', '__getattribute__', '__hash_ _', '__init__', '__module__', '__new__', '__reduce__', '__reduce_ex__', '__repr_ _', '__setattr__', '__str__', '__weakref__'] class Old: pass ... dir(Old) ['__doc__', '__module__'] As you can see there is quite a lot of extra "stuff" in the New class. In Python 3: class New(object): pass dir(New) ['__class__', '__delattr__', '__dict__', '__doc__', '__eq__', '__format__', '__ge__', '__getattribute__', '__gt__', '__hash__', '__init__', '__le__', '__lt__', '__module__', '__ne__', '__new__', '__reduce__', '__reduce_ex__', '__repr__', '__setattr__', '__sizeof__', '__str__', '__subclasshook__', '__weakref__'] class Old: pass dir(Old) ['__class__', '__delattr__', '__dict__', '__doc__', '__eq__', '__format__', '__ge__', '__getattribute__', '__gt__', '__hash__', '__init__', '__le__', '__lt__', '__module__', '__ne__', '__new__', '__reduce__', '__reduce_ex__', '__repr__', '__setattr__', '__sizeof__', '__str__', '__subclasshook__', '__weakref__'] There is even more "stuff" but it is the same with/without the explicit 'object'. HTH, -- Alan Gauld Author of the Learn to Program web site http://www.alan-g.me.uk/ ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: http://mail.python.org/mailman/listinfo/tutor
[Tutor] Subclassing object
I read that it is advised to subclass object. Is it really necessary? I mean, everything works, why should I add it to my code? Cheers, Timo ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: http://mail.python.org/mailman/listinfo/tutor
[Tutor] Confirmation about __init__()
I have read quite a bit in the past 2 months, ( I have also looked at codes) At this point, I think I understand well what __init__() is and does - But, I have yet to see this *specifically* spelled out about the the __init__ method for a Class; It is OPTIONAL, correct ? if I have NO start values/variables to set, no Base Class __init__ to call --- the __init__ method is NOT required, correct ? thanks ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] command line invocation
"Robert" wrote in shell, my current directory is "/tmp", are line#3 and #4 --- http://paste.pocoo.org/show/166268/ - "equivalent" --- i.e. yielding the same result ? No need to use pastebin when its only 2 lines! Since -m runs a module as a script I think the answer is yes. Where they would be different is if you were not in the same folder as the module. Then the -m option would search the PYTHONPATH whereas without -m I think it would not search for the module, you would need to specify the location. I think... -- Alan Gauld Author of the Learn to Program web site http://www.alan-g.me.uk/ ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] Confirmation about __init__()
"Robert" wrote I have read quite a bit in the past 2 months, ( I have also looked at codes) At this point, I think I understand well what __init__() is and does - But, I have yet to see this *specifically* spelled out about the the __init__ method for a Class; It is OPTIONAL, correct ? Yes as are all metods. There is nothing very special about __init__ except that it is not called explicitly by users of the class. It could have been done as an explicit method as in Smalltalk or Objective C. In these the instance creation paradigm is a two stage process obj = [[class new] init] In Python we get the init call for "free" Alan G. ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: http://mail.python.org/mailman/listinfo/tutor
[Tutor] command line invocation
Say that I have module "spam.py" in "/tmp" which is in PYTHONPATH. in shell, my current directory is "/tmp", are line#3 and #4 --- http://paste.pocoo.org/show/166268/ - "equivalent" --- i.e. yielding the same result ? Thanks ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: http://mail.python.org/mailman/listinfo/tutor
