sam at mas.pl
Thu Mar 20 16:44:43 CET 2008
Bruno Desthuilliers napisał(a):
> Most of the arguments in favor of prototypes seems to come to, mainly:
> 1/ it lets you customize behaviour on a per-object base
> 2/ it removes the mental overhead of inheritance, classes etc
> Point 1. is a non-problem in Python, since you can already add/replace
> methods on a per-objec basis (ok, with a couple restrictions wrt/
> __magic__ methods and such).
> Point 2. is not (IMHO) such a problem in Python, where inheritance is
> mainly an implementation detail (it's not needed for polymorphic
> dispatch to work) and class hierarchy tend to be very flat, when they
> even exist.
> here. That is, you get more or less the same flexibility. And a couple
> attribute lookup mechanism), too.
Thanks for precise opinion and spending your time.
I think that when you use statically typed language, than you have to define
classes, because compiler has to know what is allowed to do with instances of
But when you use dynamically typed language, then classes are redundant, because
object is looked at when it is referenced. Dynamically typed language needs only
objects hierarchy and you can add properties (methods, values) to that object
during program execution.
In dynamically typed language when you create object A that is inherited from
another object B, than object A knows that B is his predecessor. So when you
reference A.prop, then prop is looked in A first, then in B, then in
predecessors of B, and so on.
Having object A you can access its predecessor B. When you have access to object
B, then you can add properties to it and these properties could be accessed by
all other objects inherited from B.
You can do all these things in Python. But why it uses classes?
So you can say: "CLASS BASED PROGRAMMING" == "STATICALY TYPED LANGUAGE"
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