Composition instead of inheritance
nagle at animats.com
Fri Apr 29 07:10:06 CEST 2011
On 4/28/2011 3:35 PM, Carl Banks wrote:
> On Thursday, April 28, 2011 10:15:02 AM UTC-7, Ethan Furman wrote:
>> For anybody interested in composition instead of multiple
>> inheritance, I have posted this recipe on ActiveState (for python
>> 2.6/7, not 3.x):
> That's not what we mean by composition. Composition is when one
> object calls upon another object that it owns to implement some of
> its behavior. Often used to model a part/whole relationship, hence
> the name.
The distinction isn't that strong in Python, where an object
can't be part of another object. Object fields are references, not
the objects themselves.
In C++, you really can have an object as a field of an enclosing
object. The inner object's destructor will be called first.
Destructors and ownership tend not to be too important in Python,
because storage management is automatic.
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