problem with references

[Uwe Mayer]

In article <MPG.179e17ffdf2208d9989684 at news.rz.uni-karlsruhe.de>, 
merkosh at hadiko.de says...
 
> !>>         cpy = copy.deepcopy(self.element)
>             try:
>                 cpy.parse(f)
>             except ParseError:                 #reached maximum hits
> 	         ....
>             else:
>                 if (<size of queue is ok>):
>                     self.value.append(cpy)
>                 ...
> 

I did "some" more debuging and came to a more precise result /question.
The error is in the copy.deepcopy() call above, but the problem is 
somewhere else.

The "element" class has a __deepcopy__() method which first makes a 
shallow copy of self.element and then deepcopies of each mutable 
instance variable. But, there is a problem with file objects. You can't 
pickle file objects, however each element as an attribute ".file" which 
takes up a file.
The __deepcopy__() method, beeing aware that file objects cannot be 
copied, decided to set self.file to None. And *this* is my actual 
problem. Setting self.file to None automatically sets the source 
elements self.file (the one I'm making the copy from) to None - which is 
perfectly right, because up until now those two objects are shallow 
copies and refer to the same self.file objects.

Some lines afterwards the copied element is tried to be parsed, fails, 
raises ParseError and is removed from the queue, leaving no trace of its 
deeds, but setting the file attribute of the elements left in self.value 
to None.

Now how am I supposed to just create a new "variable space" instead of 
that shallow copy?
All I need is a way to loosen the reference the shallow copy created. 
Please don't tell me that's not possible?!

Thanks in advance 
Uwe