"Eric Dorsey" <dors...@gmail.com> wrote
class A:
def __init__(self, name, value=1):
self.name = name
self.value = value
And now I want a subclass, one that overrides the value=1 and defaults to
value=2, how do I code that? I'm understanding subclasses that have
different methods that have different behavior, but I'm having trouble
doing
this.
Do we have to call the __init__ of the parent somehow? Is it "replaced"
or
overridden in an __init__ method of the subclass?
You replace the behaviour you want to change, but in the replaced
version you may choose to call the parent version.
This typically leads to very simple methods in the subclass, as in your
case:
def B(A):
def __init__(self, name, value=2):
A.__init__(self,name,value)
This defines a new init method which has a new default value.
It then calls the original parent init method passing the name
and value so that the A default never gets used in B instances.
The OOP topic in my tutor describes this in more detail.
--
Alan Gauld
Author of the Learn to Program web site
http://www.alan-g.me.uk/
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