Re: unexpected from/import statement behaviour
On Aug 27, 3:35 pm, Peter Otten [EMAIL PROTECTED] wrote: nisp wrote: Thanks first of all ! I read the interesting Diez's link but something still remains to me unclear, on the other hand it's clear the my problem is concentrated there and on symbols. Read it again. If you have two modules module1.py from sys import stderr module2.py from module1 import stderr you get three names 'stderr' in three different namespaces, and each name may bind a different object. Here is what I'm trying to do HelloWorld.py: this is a real simplification of my external module though still reflecting its structure (commented out is the version that, let's say, works) from sys import stderr #import sys class Cheers: def __init__(self): self.cheersMsg = 'Hello World !!' print Cheers stderr %s % stderr #print Cheers stderr %s % sys.stderr def _putCheers(self): printstderr, 'Here is my msg:', self.cheersMsg printstderr, 'This is a nice day today !!' #printsys.stderr, 'Here is my msg:', self.cheersMsg #printsys.stderr, 'This is a nice day today !!' def doSomeStuff(self): self._putCheers() And below there is the module that uses the above one (mymodule.py): #!/usr/bin/python import sys This imports HelloWorld.stderr: from HelloWorld import * You now have a global variable 'stderr' in module __main__, initialized to the same value as HelloWorld.stderr. class StderrCatcher: def __init__(self): self.data = '' def write(self,stuff): self.data = self.data + \t + stuff def main(): print mymodule stderr: %s % sys.stderr This rebinds sys.stderr and a local 'stderr' in main() sys.stderr = stderr = StderrCatcher() but both HelloWorld.stderr and __main__.stderr are unaffected. What you need is import HelloWorld sys.stderr = HelloWorld.stderr = StderrCatcher() m = Cheers() m.doSomeStuff() print stderr: \n%s % sys.stderr.data if __name__ == '__main__': main() Below there is the output when it doesn't work: mymodule stderr: open file 'stderr', mode 'w' at 0xb7d160b0 Cheers stderr open file 'stderr', mode 'w' at 0xb7d160b0 Here is my msg: Hello World !! This is a nice day today !! stderr: And here when it works: mymodule stderr: open file 'stderr', mode 'w' at 0xb7dc40b0 Cheers stderr __main__.StderrCatcher instance at 0xb7d8bd4c stderr: Here is my msg: Hello World !! This is a nice day today !! Thanks again! PS Sorry for having probably replied to somone of you directly :-( Hi Peter! Definitely you are right ! May be this time I understood completely the topic (or may be not ?... gosh !) ... I didn't considered well the from HelloWolrd import * in mymodule.py. Now my module is: import sys import HelloWorld class StderrCatcher: def __init__(self): self.data = '' def write(self,stuff): self.data = self.data + \t + stuff def main(): print mymodule stderr: %s % sys.stderr mystderr = sys.stderr = HelloWorld.stderr = StderrCatcher() m = HelloWorld.Cheers() m.doSomeStuff() print sys.stderr, mymodule prints something print stderr: \n%s % mystderr.data if __name__ == '__main__': main() and its output is: mymodule stderr: open file 'stderr', mode 'w' at 0xb7d2d0b0 Cheers stderr __main__.StderrCatcher instance at 0xb7cf4e4c stderr: Here is my msg: Hello World !! This is a nice day today !! mymodule prints something now it works perfectly ! Great ! Thanks to all of you ! Nisp -- http://mail.python.org/mailman/listinfo/python-list
unexpected from/import statement behaviour
Hi all ! I'm trying to capture stderr of an external module I use in my python program. I'm doing this by setting up a class in my module overwriting the stderr file object method write. The external module outputs to stderr this way: from sys import std err print stderr, Some text While in my module I use import sys . sys.stderr ... sys.stdout Well, as long as I do not change in the external module those from/ import statements to just import sys print sys.stderr, Some text I'm not able to capture its stderr and of course I would like not to do this kind of change. I've always been convinced of the equivalence of the two ways of using the import statement but it's clear I'm wrong :-( Please, someone can tell me what's going on ? Thanks in advance ! -- http://mail.python.org/mailman/listinfo/python-list
Re: unexpected from/import statement behaviour
nisp schrieb: Hi all ! I'm trying to capture stderr of an external module I use in my python program. I'm doing this by setting up a class in my module overwriting the stderr file object method write. The external module outputs to stderr this way: from sys import std err print stderr, Some text While in my module I use import sys . sys.stderr ... sys.stdout Well, as long as I do not change in the external module those from/ import statements to just import sys print sys.stderr, Some text I'm not able to capture its stderr and of course I would like not to do this kind of change. I've always been convinced of the equivalence of the two ways of using the import statement but it's clear I'm wrong :-( Please, someone can tell me what's going on ? http://effbot.org/zone/import-confusion.htm Diez -- http://mail.python.org/mailman/listinfo/python-list
Re: unexpected from/import statement behaviour
nisp [EMAIL PROTECTED] wrote: I've always been convinced of the equivalence of the two ways of using the import statement but it's clear I'm wrong :-( Python 2.5.2 (r252:60911, Jul 31 2008, 17:28:52) [GCC 4.2.3 (Ubuntu 4.2.3-2ubuntu7)] on linux2 Type help, copyright, credits or license for more information. from sys import stderr import sys sys.stderr is stderr True Behaviourly, I'm finding no difference between the two either. Could you cut paste a minimal example that isn't producing the correct behaviour, and perhaps mention what type of OS you're using? -- http://mail.python.org/mailman/listinfo/python-list
Re: unexpected from/import statement behaviour
alex23 schrieb: nisp [EMAIL PROTECTED] wrote: I've always been convinced of the equivalence of the two ways of using the import statement but it's clear I'm wrong :-( Python 2.5.2 (r252:60911, Jul 31 2008, 17:28:52) [GCC 4.2.3 (Ubuntu 4.2.3-2ubuntu7)] on linux2 Type help, copyright, credits or license for more information. from sys import stderr import sys sys.stderr is stderr True Behaviourly, I'm finding no difference between the two either. Could you cut paste a minimal example that isn't producing the correct behaviour, and perhaps mention what type of OS you're using? You did not read this part of the post: I'm not able to capture its stderr and of course I would like not to do this kind of change. He tries to set sys.stderr to a new stream and capture the print statements, but fails to do so because he created a local alias. Diez -- http://mail.python.org/mailman/listinfo/python-list
Re: unexpected from/import statement behaviour
nisp wrote: Hi all ! I'm trying to capture stderr of an external module I use in my python program. I'm doing this by setting up a class in my module overwriting the stderr file object method write. The external module outputs to stderr this way: from sys import std err print stderr, Some text While in my module I use import sys . sys.stderr ... sys.stdout Well, as long as I do not change in the external module those from/ import statements to just import sys print sys.stderr, Some text I'm not able to capture its stderr and of course I would like not to do this kind of change. I've always been convinced of the equivalence of the two ways of using the import statement but it's clear I'm wrong :-( Please, someone can tell me what's going on ? Thanks in advance ! A practical approach to complement Diez' link to the explanation: Instead of modifying the external module you can either redirect stderr before you import the external module import sys sys.stderr = whatever import external or monkey-patch: import sys import external sys.stderr = external.sterr = whatever Peter -- http://mail.python.org/mailman/listinfo/python-list
Re: unexpected from/import statement behaviour
On Aug 27, 9:56 am, Peter Otten [EMAIL PROTECTED] wrote: nisp wrote: Hi all ! I'm trying to capture stderr of an external module I use in my python program. I'm doing this by setting up a class in my module overwriting the stderr file object method write. The external module outputs to stderr this way: from sys import std err print stderr, Some text While in my module I use import sys . sys.stderr ... sys.stdout Well, as long as I do not change in the external module those from/ import statements to just import sys print sys.stderr, Some text I'm not able to capture its stderr and of course I would like not to do this kind of change. I've always been convinced of the equivalence of the two ways of using the import statement but it's clear I'm wrong :-( Please, someone can tell me what's going on ? Thanks in advance ! A practical approach to complement Diez' link to the explanation: Instead of modifying the external module you can either redirect stderr before you import the external module import sys sys.stderr = whatever import external or monkey-patch: import sys import external sys.stderr = external.sterr = whatever Peter Hi all ! Thanks first of all ! I read the interesting Diez's link but something still remains to me unclear, on the other hand it's clear the my problem is concentrated there and on symbols. Here is what I'm trying to do HelloWorld.py: this is a real simplification of my external module though still reflecting its structure (commented out is the version that, let's say, works) from sys import stderr #import sys class Cheers: def __init__(self): self.cheersMsg = 'Hello World !!' print Cheers stderr %s % stderr #print Cheers stderr %s % sys.stderr def _putCheers(self): printstderr, 'Here is my msg:', self.cheersMsg printstderr, 'This is a nice day today !!' #printsys.stderr, 'Here is my msg:', self.cheersMsg #printsys.stderr, 'This is a nice day today !!' def doSomeStuff(self): self._putCheers() And below there is the module that uses the above one (mymodule.py): #!/usr/bin/python import sys from HelloWorld import * class StderrCatcher: def __init__(self): self.data = '' def write(self,stuff): self.data = self.data + \t + stuff def main(): print mymodule stderr: %s % sys.stderr sys.stderr = stderr = StderrCatcher() m = Cheers() m.doSomeStuff() print stderr: \n%s % sys.stderr.data if __name__ == '__main__': main() Below there is the output when it doesn't work: mymodule stderr: open file 'stderr', mode 'w' at 0xb7d160b0 Cheers stderr open file 'stderr', mode 'w' at 0xb7d160b0 Here is my msg: Hello World !! This is a nice day today !! stderr: And here when it works: mymodule stderr: open file 'stderr', mode 'w' at 0xb7dc40b0 Cheers stderr __main__.StderrCatcher instance at 0xb7d8bd4c stderr: Here is my msg: Hello World !! This is a nice day today !! Thanks again! PS Sorry for having probably replied to somone of you directly :-( -- http://mail.python.org/mailman/listinfo/python-list
Re: unexpected from/import statement behaviour
nisp wrote: On Aug 27, 9:56 am, Peter Otten [EMAIL PROTECTED] wrote: nisp wrote: Hi all ! I'm trying to capture stderr of an external module I use in my python program. I'm doing this by setting up a class in my module overwriting the stderr file object method write. The external module outputs to stderr this way: from sys import std err print stderr, Some text While in my module I use import sys . sys.stderr ... sys.stdout Well, as long as I do not change in the external module those from/ import statements to just import sys print sys.stderr, Some text I'm not able to capture its stderr and of course I would like not to do this kind of change. I've always been convinced of the equivalence of the two ways of using the import statement but it's clear I'm wrong :-( Please, someone can tell me what's going on ? Thanks in advance ! A practical approach to complement Diez' link to the explanation: Instead of modifying the external module you can either redirect stderr before you import the external module import sys sys.stderr = whatever import external or monkey-patch: import sys import external sys.stderr = external.sterr = whatever Peter Hi all ! Thanks first of all ! I read the interesting Diez's link but something still remains to me unclear, on the other hand it's clear the my problem is concentrated there and on symbols. Here is what I'm trying to do HelloWorld.py: this is a real simplification of my external module though still reflecting its structure (commented out is the version that, let's say, works) from sys import stderr This is your problem. You create a HelloWorld.stderr-alias to the object bound to sys.stderr. Rebinding the latter won't affect the former. That is precisely what the link I gave you explains. The short answer to the whole issue is: dont' use the from-import syntax until you really know what you are doing. Or not at all. Diez -- http://mail.python.org/mailman/listinfo/python-list
Re: unexpected from/import statement behaviour
On Aug 27, 2:43 pm, Diez B. Roggisch [EMAIL PROTECTED] wrote: nisp wrote: On Aug 27, 9:56 am, Peter Otten [EMAIL PROTECTED] wrote: nisp wrote: Hi all ! I'm trying to capture stderr of an external module I use in my python program. I'm doing this by setting up a class in my module overwriting the stderr file object method write. The external module outputs to stderr this way: from sys import std err print stderr, Some text While in my module I use import sys . sys.stderr ... sys.stdout Well, as long as I do not change in the external module those from/ import statements to just import sys print sys.stderr, Some text I'm not able to capture its stderr and of course I would like not to do this kind of change. I've always been convinced of the equivalence of the two ways of using the import statement but it's clear I'm wrong :-( Please, someone can tell me what's going on ? Thanks in advance ! A practical approach to complement Diez' link to the explanation: Instead of modifying the external module you can either redirect stderr before you import the external module import sys sys.stderr = whatever import external or monkey-patch: import sys import external sys.stderr = external.sterr = whatever Peter Hi all ! Thanks first of all ! I read the interesting Diez's link but something still remains to me unclear, on the other hand it's clear the my problem is concentrated there and on symbols. Here is what I'm trying to do HelloWorld.py: this is a real simplification of my external module though still reflecting its structure (commented out is the version that, let's say, works) from sys import stderr This is your problem. You create a HelloWorld.stderr-alias to the object bound to sys.stderr. Rebinding the latter won't affect the former. That is precisely what the link I gave you explains. The short answer to the whole issue is: dont' use the from-import syntax until you really know what you are doing. Or not at all. Diez Hi Diez! I well understand the problem now, the fact is that unfortunately the external module is not mine and i doubt i can change it :-( Anyway as far as i'm concerned i've learned the lesson ! Thanks again and greetings, Nisp -- http://mail.python.org/mailman/listinfo/python-list
Re: unexpected from/import statement behaviour
nisp wrote: Thanks first of all ! I read the interesting Diez's link but something still remains to me unclear, on the other hand it's clear the my problem is concentrated there and on symbols. Read it again. If you have two modules module1.py from sys import stderr module2.py from module1 import stderr you get three names 'stderr' in three different namespaces, and each name may bind a different object. Here is what I'm trying to do HelloWorld.py: this is a real simplification of my external module though still reflecting its structure (commented out is the version that, let's say, works) from sys import stderr #import sys class Cheers: def __init__(self): self.cheersMsg = 'Hello World !!' print Cheers stderr %s % stderr #print Cheers stderr %s % sys.stderr def _putCheers(self): printstderr, 'Here is my msg:', self.cheersMsg printstderr, 'This is a nice day today !!' #printsys.stderr, 'Here is my msg:', self.cheersMsg #printsys.stderr, 'This is a nice day today !!' def doSomeStuff(self): self._putCheers() And below there is the module that uses the above one (mymodule.py): #!/usr/bin/python import sys This imports HelloWorld.stderr: from HelloWorld import * You now have a global variable 'stderr' in module __main__, initialized to the same value as HelloWorld.stderr. class StderrCatcher: def __init__(self): self.data = '' def write(self,stuff): self.data = self.data + \t + stuff def main(): print mymodule stderr: %s % sys.stderr This rebinds sys.stderr and a local 'stderr' in main() sys.stderr = stderr = StderrCatcher() but both HelloWorld.stderr and __main__.stderr are unaffected. What you need is import HelloWorld sys.stderr = HelloWorld.stderr = StderrCatcher() m = Cheers() m.doSomeStuff() print stderr: \n%s % sys.stderr.data if __name__ == '__main__': main() Below there is the output when it doesn't work: mymodule stderr: open file 'stderr', mode 'w' at 0xb7d160b0 Cheers stderr open file 'stderr', mode 'w' at 0xb7d160b0 Here is my msg: Hello World !! This is a nice day today !! stderr: And here when it works: mymodule stderr: open file 'stderr', mode 'w' at 0xb7dc40b0 Cheers stderr __main__.StderrCatcher instance at 0xb7d8bd4c stderr: Here is my msg: Hello World !! This is a nice day today !! Thanks again! PS Sorry for having probably replied to somone of you directly :-( -- http://mail.python.org/mailman/listinfo/python-list
Re: unexpected from/import statement behaviour
On Aug 27, 5:42 pm, Diez B. Roggisch [EMAIL PROTECTED] wrote: alex23 schrieb: nisp [EMAIL PROTECTED] wrote: I've always been convinced of the equivalence of the two ways of using the import statement but it's clear I'm wrong :-( Python 2.5.2 (r252:60911, Jul 31 2008, 17:28:52) [GCC 4.2.3 (Ubuntu 4.2.3-2ubuntu7)] on linux2 Type help, copyright, credits or license for more information. from sys import stderr import sys sys.stderr is stderr True Behaviourly, I'm finding no difference between the two either. Could you cut paste a minimal example that isn't producing the correct behaviour, and perhaps mention what type of OS you're using? You did not read this part of the post: I'm not able to capture its stderr and of course I would like not to do this kind of change. He tries to set sys.stderr to a new stream and capture the print statements, but fails to do so because he created a local alias. No, I read it, I just totally didn't parse it that way :) Sorry for the confusion, nisp. -- http://mail.python.org/mailman/listinfo/python-list
