import order or cross import

[Jussi Salmela]

Roland Hedberg kirjoitti:
> Hi!
> 
> I'm having a bit of a problem with import.
> 
> I'm writing a marshalling system that based on a specification will
> create one or more files containing mostly class definitions.
> 
> If there are more than one file created (and there are reasons for
> creating more than one file in some instances) then they will import
> each other since there may be or is interdependencies in between them.
> 
> And this is where the going gets tough.
> 
> Let's assume I have the following files:
> 
> ------------- ONE.py --------------------
> 
> import TWO
> 
> class Car:
>     def __init__(self):
>         self.color = None
> 
>     def set_color(self,v):
>         if isinstance(v,TWO.Black) or isinstance(v,TWO.White):
>             self.color = v
> 
> class BaseColor:
>     def __init__(self):
> 	pass
>     def __str__(self):
>         return self.color
> 
> if __name__ == "__main__":
>     car = Car()
>     color = TWO.Black()
>     car.set_color(color)
>     print car.color
> 
> -------------- TWO.py -------------------
> 
> import ONE
> 
> class Black(ONE.BaseColor):
>     color = "Black"
>     def __init__(self):
>         ONE.BaseColor.__init__(self)
> 
> class White(ONE.BaseColor):
>     color = "White"
>     def __init__(self):
>         ONE.BaseColor.__init__(self)
> 
> -----------------------------------------
> 
> Now, running ONE.py causes no problem it will print "Black", but running
> TWO.py I get:
> AttributeError: 'module' object has no attribute 'BaseColor'
> 
> So, how can this be solved if it can be ?
> 
> To join ONE.py and TWO.py into one file could be a solution if there
> where no other conditions (non-language based) that prevented it.
> 
> -- Roland
> 

Maybe I'm missing something, but why is the class BaseColor in file 
ONE.py and not in TWO.py?

Cheers,
Jussi