A class question

[Gabriel Genellina]

En Tue, 30 Oct 2007 02:51:39 -0300, Donn Ingle <donn.ingle at gmail.com>  
escribió:

>> While Java's variable declarations bear a superficial (syntactical)
>> similarity to C, their semantics is in fact equivalent to the
>> object-reference semantics we know in Python.
>
> I come from Z80A/GWBASIC/VB and a little C, I would describe a Python
> variable as a pointer - in that it contains the address of something.
> What that "something" is, is a little fuzzy. Right now I imagine it's to  
> a
> kind of structure which has meta info about the object as well as it's
> actual address.
>
> How far off would that be?

Almost true. A Python variable is a name inside a namespace, pointing to a  
Python object. Many names may point to the same object, of course.
An object (in CPython) is a structure containing a reference count,  
followed by a pointer to the object's type, followed by the object  
contents itself. The object contents may as simple as a single value (e.g.  
int or float objects) or rather complex (like the frame object which  
contains about 18 other values, including many pointers to other  
structures and arrays).
The object's type would be what you call the meta info, and contains the  
type name, many pointers to functions (implementing the type methods) and  
some flags describing the type behavior.

-- 
Gabriel Genellina