inheritance problem

Mike C. Fletcher mcfletch at rogers.com
Tue Oct 1 18:26:19 CEST 2002


Python 2.2 has a function called super...

super(type) -> unbound super object
super(type, obj) -> bound super object; requires isinstance(obj, type)
super(type, type2) -> bound super object; requires issubclass(type2, type)

Which lets you call the super-class (base-class) method like so:

	super( InheritedClass, self).methodname( arg1, arg2 )

Before Python 2.2, this was done by explicitly naming the super-class:

	BaseClass.methodname( self, arg1, arg2 )

As a note, though, in BaseClass methods called for an InheritedClass, 
the method-lookup is via run-time _name_ lookup, so you get whatever the 
object (the InheritedClass instance) says it's various methods are.

As an example:

class A( object ):
     def a( self ):
         return self.b()
     def b( self ):
         return 'A'
class B( A ):
     def b( self ):
         return 'B'
class C( A ):
     def b( self ):
         return super(C,self).b()+'C'

print A().a()
print B().a()
print C().a()

Will print:
A
B
AC

HTH,
Mike

gabor wrote:
...
> then i created an inherited class (let's call it InheritedClass):
> 	and override displayData
> 
> 	but there's the problem:
> 	in that windowIDdictionary, the type of the self's is BaseClass,
> 	so it won't call InheritedClass's methods :-((((
> 
> any ideas how to do this correctly?
> as i know there is nothing like casting in python :-((
> 
> i have some solutions like the inerited class's constructor will have to
> manually call a method in the baseclass.... but i wanted to make it a
> way, so the inherited class doesn't have to deal with the baseclass,
> except for the constructor...
> 
> thanks,
> gabor
> 
_______________________________________
   Mike C. Fletcher
   Designer, VR Plumber, Coder
   http://members.rogers.com/mcfletch/






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