passing by refference

[Donn Cave]

Quoth Joshua Marshall <joshway_without_spam at myway.com>:
...
| See
|
|   http://wombat.doc.ic.ac.uk/foldoc/foldoc.cgi?call-by-value
|
| What you describe is call-by-value.  There is an implicit copy of the
| arguments passed to a function, though not a deep-copy.  The values
| that are being copied are often references.

That's a clever analysis - ``the values that are being copied are
often references'', indeed.

The only really 100% answer to this question - does Python pass by
value or by reference - is "No!"  Then one can approach this subject
with a fresh mind unimpeded by the baggage of other programming
languages (and FOLDOC.)

The ``values that are being copied'' are _always_ references.
The result of an operation on this reference from within the function,
is identical to the same operation outside it - if I pass a parameter
"x" and then assign to it "x = 5", in either case, x is a reference
and I replace the original "x" with a new one.  The only difference
is that the function and its caller bind to different namespaces.
Operations on the object - methods, indexing etc - apply to the original
object, namespace binding applies to the current namespace.
Is it call by reference, or call by value?  No!

	Donn Cave, donn at u.washington.edu