Marvin wrote:
> Hi,
>
> It's been claimed
s/claimed/observed/
In Python and Ruby, class hierarchies tends to be *really* flat when
compared to Java or C++.
> that inheritance structures are less important in dynamic
> languages like Python. Why is that
Don't you guess ?-)
A very obvious point is that in a dynamically typed language,
inheritence is only about implementation - it's not used for class-based
polymorphism (subtyping).
Also, dynamic languages are usually very strong on introspection and
offer good support for automatic delegation ("DoesNotUnderstand" in
Smalltalk, __getattr__ in Python, etc), which tend to lower the use of
inheritence for "private inheritence" (ie: implementation reuse without
any subtyping semantic).
This leaves with only three real use-case for inheritence :
* factoring common features of a set of related classes in an abstract
base class
* specialisation of an existing class (proper subclassing),
* mixins.
> and where can i read more about that?
"duck typing", "implied interface" and "composition/delegation" could be
good starting points for a google search.
--
bruno desthuilliers
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