[Edu-sig] python versus __python__

Arthur ajsiegel at optonline.net
Sun Oct 23 23:23:20 CEST 2005

Scott David Daniels wrote:

>Arthur 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
>a copy.  
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
>PyGeoTriangle(<some args>). 
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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