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From: Marko Rauhamaa <marko@pacujo.net>
Newsgroups: comp.lang.python
Subject: Re: Building CPython
Date: Sat, 16 May 2015 11:08:25 +0300
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BartC <bc@freeuk.com>:

> I suppose in many cases an object will have no attributes of its own,
> and so it can rapidly bypass the first lookup.

Almost all objects have quite many instance attributes. That's what
tells objects apart.

> I don't understand the need for an object creation (to represent A.B
> so that it can call it?) but perhaps such an object can already exist,
> prepared ready for use.

Note that almost identical semantics could be achieved without a class.
Thus, these two constructs are almost identical:

    class C:
        def __init__(self, x):
            self.x = x

        def square(self):
            return self.x * self.x

        def cube(self):
            return self.x * self.square()

    ##

    class O: pass

    def C(x):
        o = O()

        def square():
            return x * x

        def cube():
            return x * square()

        o.square = square
        o.cube = cube
        return o


IOW, the class is a virtually superfluous concept in Python. Python has
gotten it probably without much thought (other languages at the time had
it). I comes with advantages and disadvantages:

 + improves readability

 + makes objects slightly smaller

 + makes object instantiation slightly faster

 - goes against the grain of ducktyping

 - makes method calls slower

 - makes method call semantics a bit tricky


Marko