What other languages use the same data model as Python?

[Terry Reedy]

On 5/1/2011 6:33 PM, Gregory Ewing wrote:
> Steven D'Aprano wrote:
>
>> Python uses a data model of "name binding" and "call by object" (also
>> known as "call by sharing").
>
> It can be summed up in a less jargony way by saying that all
> data is stored in heap-allocated objects,

This is incomprehensible jargon to some; is only (partly) true of 
(typical) machine-implementations; and seems not to be true of all 
objects. I believe that for CPython, builtin objects, including the 
fixed arrray of ints from -5 to 256, are allocated in another data 
segment (more CS jargon, which is irrelavant to human interpreters).

Evidence 1:
 >>> id(int)
505285072
 >>> id(str)
505233232
 >>> id(1)
505493792
 >>> id(-5)
505493696

This appears to be initialized data segment. (Someone else could take a 
white box approach and look at the source. ;-)

 >>> id(333333)
16512288
 >>> id('a')
11227616

This is heap.

Evidence 2:
Some error messages use 'heap type' to mean 'Python-coded class'

 >>> 1 .__class__ = str
Traceback (most recent call last):
   File "<pyshell#8>", line 1, in <module>
     1 .__class__ = str
TypeError: __class__ assignment: only for heap types

http://bugs.python.org/issue4600

 > and variables refer  to objects rather than containing them directly.
 > Everything else follows from that.

Would you say 'names refer to objects rather than containing them 
directly'? Surely not. Using 'name' rather than the hugely overloaded 
tern 'variable' automatically avoids certain misunderstandings.

A good summary might be "Python manipulates objects that are accessed 
through literals, names, and expressions."
-- 
Terry Jan Reedy