references ???

[Chris Gonnerman]

----- Original Message ----- 
From: "Thomas Weidner" <wolf359_ at gmx.net>


> In <9rtpsc$13j2 at newton.cc.rl.ac.uk>, Richard Brodie wrote:

> > Implicitly. Consider the following:
> > 
> >>>> a = [1,2,3]
> >>>> b = a
> >>>> b[1] = 20
> >>>> print a
> > [1, 20, 3]
> 
> Interesting....
> Is this also possible for single values like ints ?

Not exactly.  Consider:

>>> a = 1       # a is reference to scalar integer 1
>>> b = a       # b is reference to same scalar integer 1
>>> b = 2       # b is rebound to scalar integer 2
>>> print a     # a is still bound where it was before
1

In effect, all Python variables are references (pointers in other
words) to objects; even the simple number 1 is stored internally
as an object.  The assignment statement, assigning to a simple
name, rebinds the name to a different object.

What you want, therefore, is the same as a reference to a reference
to a scalar object.  Python doesn't do that; generally, it's not
needed.

You will see, from time to time, mentions on this list about
thinking Pythonically.  When you master that you won't miss painful
complexities like nested references.