Gabriel Genellina wrote:
En Tue, 28 Oct 2008 00:58:10 -0200, greg <[EMAIL PROTECTED]> escribió:
>
(1) Call by value: The actual parameter is an expression. It is evaluated and the result is assigned to the formal parameter. Subsequent assignments to the formal parameter do not affect the actual parameter.(2) Call by reference: The actual parameter is an lvalue. The formal parameter becomes an alias for the actual parameter, so that assigning to the formal parameter has the same effect as assigning to the actual parameter.Those definitions are only applicable to unstructured, primitive types, where the only relevant operations are "get value" and "assign value". Structured types provide other operations too - like selection (attribute get/set in Python).
But that isn't what "assigning to the formal parameter" means -- it only means assigning directly to the parameter *name*.
It is unspecified on both definitions above what happens in those cases.
That's true, but it's outside the scope of the parameter passing mechanism to define what happens in those cases. That's down to the data model being used by the language and the semantics of assignment in general. -- Greg -- http://mail.python.org/mailman/listinfo/python-list
