inheritance?

[KraftDiner]

Steven D'Aprano wrote:
> On Tue, 15 Aug 2006 19:35:11 -0700, KraftDiner wrote:
>
> > I have two classes:
> >
> > class implicitClass:
> >    def __init__(self):
> >    def isIVR(self):  #This is a class private method.
>
> The convention is to flag classes as "private" with a leading underscore:
>
>     def _isIVR(self):
>
> or double underscores for "really private, no, honestly":
>
>     def __isIVR(self):
>
> but google on "python name mangling" before using that.
>
> [snip]
>
> > As you can see the interface is almost identical.
> >
> > How can I define a base class that will abstract
> > the type such that I don't know if its really and inplicit
> > or explicit object?
>
> Something like this?
>
>
> class baseClass:
>    def __init__(self):
>        raise NotImplementedError("Don't instantiate the base class!")
>    def fromfile(self):
>    def getElement(self):
>    # etc.
>
>
> class implicitClass(baseClass):
>    def __init__(self):
>        # code
>    def _isIVR(self):
>        # code
>    def fromfile(self, fileObj, byteOrder):
>        # code
> # etc.
>
> Now, you can define instance = implicitClass() or explicitClass(). When
> you come to use instance, you don't need to know whether it is one or the
> other. If you need to type-test, call "isinstance(instance, baseClass)".
>
> The only minor issue is that the fromfile method has a different
> interface. If you really want to do duck typing, they need to have the
> same interface. That might be as simple as:
>
> class explicitClass(baseClass):
>    def fromfile(self, fileObj, byteOrder=None):
>        # byteOrder is ignored; it is included only for
>        # compatibility with implicitClass
>
>
> Is that what you're asking for?
>
Yes I believe so but in fromfile I want to call the appropriate
method depending on the in a parameter in fromfile...
like:
class baseClass:
   def fromfile(self, fileObj, byteOrder=None, explicit=False):
      if explicit:
         call fromfile of explicit class
      else:
        call fromfile of implicit class

How is that done?


> 
> 
> -- 
> Steven D'Aprano