trouble understanding inheritance...

[Steven D'Aprano]

On Wed, 16 Aug 2006 12:53:12 -0700, KraftDiner wrote:

>> > Well how does one select which class baseClass really is when you
>> > contruct the object?
>> > What am I missing?
>> >
>> > a = typeA()
>> > b = typeB()
>> > c = baseClass(a)
>>
>> a = typeA()
>> b = typeB()
>>
>> You're done. Stop there.
>>
> I can see that this might work...
> c = [a, b]
> for c in [a,b]:
>    c.getName()
> 
> but when does baseClass ever get used?
> Why did i even have to define it?

So that you don't duplicate code. That's it.

Here is a basic example. I have a class Foo with a method foo() that
returns "foo", and a second class Foos which is *almost* the same except
method foo() takes an argument and returns that number of foos.

class BaseClass():
    def foo(self):
        return "foo"

class Foo(BaseClass):
    def foo(self):
        return self.__class__.foo() # call the parent class method

class Foos(BaseClass):
    def foo(self, n):
        return self.__class__.foo() * n


Obviously in this case, there is no real need for BaseClass -- Foos could
inherit from Foo. But in more complex cases, you might need something like
this.

Hope this helps.


-- 
Steven D'Aprano