Finding the instance reference of an object

[greg]

Arnaud Delobelle wrote:

>     // What is passed to foo below is obviously not a 'variable
>     // reference' as the argument is not a variable.
>     foo(a[3]); // Now a[3] == 7
>     foo(b.i);  // Now b.i == 7

Yes, it is. By "variable" I mean what C calls an lvalue,
i.e. something you can assign to.

> I'm not sure that your definition of 'call by value' is widely
> accepted.  If it was, then this thread wouldn't exist.

It seems to be accepted by the Java and VB community,
judging by what they refer to as call-by-value in those
languages.

You won't necessarily find it written down anywhere in
the exact words I used. I have reverse-engineered it
from the characteristics of a wide variety of languages
that use the term call-by-value to describe one of their
parameter passing mechanisms. Think of it as a theory
that fits the observed linguistic facts.

>     (CBV) An evaluation strategy where arguments are evaluated before
>     the function or procedure is entered. Only the values of the
>     arguments are passed and changes to the arguments within the called
>     procedure have no effect on the actual arguments as seen by the
>     caller.

That hinges on what exactly is meant by "changes to
the arguments". In Python it can only mean assigning
directly to the bare name -- anything else isn't
changing the argument itself, but something else to
which the argument refers.

-- 
Greg