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From: "R. Michael Weylandt" <michael.weylandt@gmail.com>
Date: Sun, 16 Jun 2013 11:42:36 +0100
Subject: Re: A certainl part of an if() structure never gets executed.
To: Nick the Gr33k <support@superhost.gr>
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On Sun, Jun 16, 2013 at 10:59 AM, Nick the Gr33k <support@superhost.gr> wro=
te:
> On 16/6/2013 12:22 =EC=EC, Denis McMahon wrote:
>>
>> For example, in Python
>>
>> a =3D 6
>> b =3D a
>> c =3D 6
>>
>> a and b point to one memory location that contains the value 6
>> c points to a different memory location that contains the value 6
>
>
> I believe you are mistaken.
>
> a here is not a pointer but variable,
> which is a memory location that stores value 6.
>
> b here is a pointer. It's value is the memory location of variable a whic=
h
> stores value 6.
>
> c here is just te same as a , a variable.

Actually, y'all both might be. This is a bit CPython specific and not
mandated by the language specification.

To Nikos: please don't extrapolate from the examples below. They are a
CPython (the most common implementation of the Python language)
specific detail.

## CODE SNIPPET##
a =3D 6; b =3D a; c =3D 6

id(a)
id(b)
id(c)
## END CODE##

These are all the same, indicating that they all point to the "same 6"
in memory. That's a CPython specific optimization (caching small
integers) which is not guaranteed by the language and changes between
pythons and between compiles.

For example,

## CODE SNIPPET##
a =3D 552315251254
b =3D a
c =3D  552315251254

a is b # True _on my machine_
a is c # False _on my machine_

id(a)
id(b)
id(c)
## END CODE##

Note that to compare if two names point to the same "object, you can
use the "is" operator.

a is b
c is a

etc.

>
>>> A pointer =3D a variable that has as a value a memory address a variabl=
e =3D
>>> a memory address that has as a value the actual value we want to store.
>>
>>
>> These are really C terms, not Python terms. Stop thinking that C is
>> behaving like Python.
>
>
>
> I think it behaves the same way, but lets here from someone else too.

I understand the Greeks invented democracy and all that, but facts
aren't subject to it.

>
> Whats the difference of "interpreting " to "compiling" ?

If only it could be googled.... Alas, no one has ever written anything
about technology on the internet. Ironic that...

Michael