a simple question about class composition

[Shaun Koerber]

Hi David,

I tried this code out on windows xp and it seemed to work fine.  I'm using
python 2.2.2 mind you, so you *might* just need an upgrade.  However, it
also occurred to me that a different myclass.py may be defined in a
different directory of sys.path.  I've just begun learning python a couple
months ago, and I experienced this phenomena with 2 "test.py" scripts.
Needless to say, the one I *didn't* want to test was imported.  Anyway, hope
that some of this helps.

Shaun.

"David Schonberger" <schond at eecs.ku.edu> wrote in message
news:mailman.1038445791.28128.python-list at python.org...
> I have the following two class definitions in a file called myclass.py:
>
> ###begin###
>
> class MyClass:
>     def __init__(self, txt):
>         self.text = txt
>     def printText(self):
>         print "Text for MyClass " + str(self.text) + "\n"
>
> class MyOtherClass:
>     def __init__(self,txt):
>         self.text = txt
>     def printText2(self):
>         print "Twice the text for MyOtherClass " + str(2*self.text) + "\n"
>
> ###end###
>
> I then have the following code in a file called mycontainerclass.py:
>
> ###begin###
>
> from myclass import *
>
> class MyContainerClass:
>     def __init__(self, txt):
>         self.text = txt
>         self.one = MyClass(" I like Vanilla Coke")
>         self.two = MyOtherClass("I like Classic Coke")
>
>
>     def printContainerText(self):
>         print "Container class text " + str(self.text) + "\n"
>
>     def invokePrint(self):
>         self.one.printText()
>         self.two.printText2()
>
> if __name__ == "__main__":
>    myobj = MyContainerClass("I like both Vanilla Coke and Classic Coke")
>    myobj.invokePrint()
>    myobj.printContainerText()
>
> ###end###
>
> When I try to run this code for MyContainerClass I get the following
> error:
>
> ###begin###
>
> Traceback (most recent call last):
>   File "C:/Python22/mycontainerclass.py", line 18, in ?
>     myobj = MyContainerClass("I like both Vanilla Coke and Classic Coke")
>   File "C:/Python22/mycontainerclass.py", line 7, in __init__
>     self.two = MyOtherClass("I like Classic Coke")
> NameError: global name 'MyOtherClass' is not defined
>
> ###end###
>
> Any idea what is happening? I came across similar code in Lutz's "Learning
> Python" (a good three years old; perhaps this is part of the problem). I
> am running Python 2.2.1 on Win2K but have run into the same problem on
> Linux. Note that if I comment out the stuff about MyOtherClass in
> MyContainerClass--i.e. the stuff having to do with self.two--everything
> works fine, with MyClass successfully embeded in MyContainerClass. Any
> help would be appreciated. Thanks.
>
> Regards,
> David
>
> *-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*
> * David Schonberger                                         *
> * Department of Electrical Engineering and Computer Science *
> * University of Kansas                                      *
> * email: schond at eecs.ukans.edu                              *
> *-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*
>
>