Re: a dummy python question
> > If that were so, Pythonistas could never write a recursive function! > > No, presumably at the writing of the edition of _Learning Python_ that > he is reading, Python did not have nested scopes in the language, yet. > One could always write a recursive function provided it was at the > top-level of the module. One could not write a recursive function inside > another function because inside inner(), it could only access two > namespaces, the one local to inner() and the module's namespace, not the > namespace of outer() where inner() is defined. Ah, that makes sense. Thanks for the clarification. -- http://mail.python.org/mailman/listinfo/python-list
Re: a dummy python question
Thanks all for replying. I finally know what's going on. -- http://mail.python.org/mailman/listinfo/python-list
Re: a dummy python question
infidel wrote: > Learning Python wrote: > >>A example in learning Python by Mark Lutz and David Ascher >> >>about function scope >> >>example like this: >> >> def outer(x): >> >> def inner(i): >>print i, >>if i: inner(i-1) >> inner(x) >> outer(3) >> >>Here supposely, it should report error, because the function inner >>cannot see itself since inner is only in local namespace of outer. > > If that were so, Pythonistas could never write a recursive function! No, presumably at the writing of the edition of _Learning Python_ that he is reading, Python did not have nested scopes in the language, yet. One could always write a recursive function provided it was at the top-level of the module. One could not write a recursive function inside another function because inside inner(), it could only access two namespaces, the one local to inner() and the module's namespace, not the namespace of outer() where inner() is defined. For the original poster: Your book is old. You will want to catch up on recent additions to the language by reading the "What's New in Python 2.x" portions of the documentation for each major revision. Specifically: http://www.python.org/doc/2.2.3/whatsnew/node9.html http://www.python.org/doc/2.2.3/whatsnew/whatsnew22.html http://www.python.org/doc/2.3.5/whatsnew/whatsnew23.html http://www.python.org/doc/2.4.1/whatsnew/whatsnew24.html -- Robert Kern [EMAIL PROTECTED] "In the fields of hell where the grass grows high Are the graves of dreams allowed to die." -- Richard Harter -- http://mail.python.org/mailman/listinfo/python-list
Re: a dummy python question
Learning Python wrote: >>>def outer(x): > > def inner(i): > print i, > if i: inner(i-1) > inner(x) > >>>outer(3) > > Here supposely, it should report error, because the function inner > cannot see itself since inner is only in local namespace of outer. There is no error. the function inner is defined recursively: It calls itself with a different value than the one it has been called with. When defining a recursive function, there are case when it calls itself and other when it does not (otherwise the recursion is infinite and the program crashes after all the memory is used). Here it does not call itself when the value given as parameter is 0 (the if fails). one can always see itself (even at definition time) > but I typed in this in python interface. It works! > it print out: > 3 2 1 0 > > If you turn this into a module file and run this > it print out > 3 2 1 0 none I suppose you wrote this down (instead of cut and paste) as the none is not capitalized. There must be something else in your module that writes the none as your code presented above should really not "as is". -- rafi "Imagination is more important than knowledge." (Albert Einstein) -- http://mail.python.org/mailman/listinfo/python-list
Re: a dummy python question
This is not reproducible under either Python 2.3.4 (UNIX), Python 2.4.1 (UNIX) or Python 2.4.1 (Windows). If you still need help, we need to know precisely what you're doing. = scope_test.py = #!/usr/bin/env python # # (insert his code, verbatim...) # if __name__=='__main__': outer(3) = end scope_test.py = [EMAIL PROTECTED] ~]$ ./scope_test.py 3 2 1 0 [EMAIL PROTECTED] ~]$ python Python 2.3.4 (#1, Feb 2 2005, 11:44:13) [GCC 3.4.3 20041212 (Red Hat 3.4.3-9.EL4)] on linux2 Type "help", "copyright", "credits" or "license" for more information. >>> from scope_test import outer >>> outer(3) 3 2 1 0 -- http://mail.python.org/mailman/listinfo/python-list
Re: a dummy python question
Learning Python wrote: > A example in learning Python by Mark Lutz and David Ascher > > about function scope > > example like this: > > >>def outer(x): > def inner(i): > print i, > if i: inner(i-1) > inner(x) > >>outer(3) > > Here supposely, it should report error, because the function inner > cannot see itself since inner is only in local namespace of outer. If that were so, Pythonistas could never write a recursive function! -- http://mail.python.org/mailman/listinfo/python-list
a dummy python question
A example in learning Python by Mark Lutz and David Ascher about function scope example like this: >>def outer(x): def inner(i): print i, if i: inner(i-1) inner(x) >>outer(3) Here supposely, it should report error, because the function inner cannot see itself since inner is only in local namespace of outer. but I typed in this in python interface. It works! it print out: 3 2 1 0 If you turn this into a module file and run this it print out 3 2 1 0 none Can anyone explain to me what's going on? Thanks BTW: I am using Python 2.3 -- http://mail.python.org/mailman/listinfo/python-list
