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Old 03-10-2010, 05:28 PM   #1
CoderMan
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Python n00b: promoting a derived class to base class?


I have an situation kind of like so: I have object b of class B, which is a derived from base class A. Is there a way I can cast or reassign object b so that it (or the new variable referring to it) it only has the interface of class A?

Obviously, polymorphism allows me to use object b anywhere as though it was simply a class A object. However, it would be a little more convenient if I could recast it as a class A object, so that I would never have to worry about unknowingly using a method from class B's interface.

In Java I would just assign object b to a Class A variable.
 
Old 03-11-2010, 12:52 AM   #2
Dan04
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It goes against the spirit of the language. Python programs rely on duck typing.

If you really want to do it, you can write an Upcast class that defines __getattribute__ appropriately.
 
Old 03-11-2010, 01:46 PM   #3
CoderMan
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Hmm. I read the link, and that makes sense. Python isn't statically typed anyway, and functions really don't care what kind of object they receive, there isn't much point in trying to recast objects in the way I described.
 
  


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