[Edu-sig] python versus __python__
ajsiegel at optonline.net
Sun Oct 23 23:23:20 CEST 2005
Scott David Daniels wrote:
>>My studies on the subject of subclassing the complex type have been quickly
>>abandoned - it becoming clear that the fact the .real and .imag are read-only
>>defeats the ideas I had for it.
>Ahh: complex is (as are bool, int, long, string, and unicode) immutable.
>Changing such types to be mutable is "nasty" -- reuse of an immutable is
>done by referring to the same object, while reuse of an immutable needs
Getting one's arms around all the practical implications of these issues
related to mutable, immutable - understanding when one should want to
retain object identity, and when one should want to break it, the full
implications of these decisions, howto implement one's intentions -
is, on one hand - I find, fundamental to getting things to actually
happen in Python as one intends, and on the other hand , challenging. It
is the fundamental reason I chafe a bit when Python is described as "easy".
Because I have had trouble with these issues from day one, it ain't day
one anymore, I still have some troubles with them and I prefer to think
that it is challenging over thinking that I am dumb.
I am going down the road of the mutable complex number with my eyes
(half) open precisely because I want the ability to change the value of
a complex number object (and it's subclasses), without changing the
identity of the object.
Is that so wrong ;)
>If you define a class named PyGeoTriangle, you create new instances with
The connection of what you are saying here to the issue on which I am
particularly confused is - well - confusing, to me.
In Arthur's head there is the numeric type "float", and there is the
function float() - both built in. And in Arthur's head, while
functions are first class objects in Python they are objects of a
different nature than type in the sense of numeric type. So in some
sense what I am not grasping is how class/type unification can be
inclusive of verb - i.e, float(1) - and noun - i.e., type(1.) -
unification - which in Arthur's head, is something else again.
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