call by reference howto????

[sturlamolden]

On 28 Feb, 02:24, Steven D'Aprano <st... at REMOVE-THIS-

cybersource.com.au> wrote:
> Python doesn't do call by reference. Nor does it do call by value. Please
> pay no attention to anyone who says it does.

Exactly. Python pass variables the same way as Lisp, which is neither
"call-by-value" (cf. C) nor "call-by-reference" (cf. Fortran).

The Python equivalent of "pass by reference" is a function that
returns its arguments to the caller:

def foobar(arg1, arg2, arg3):

   # Mutate an object shared with the caller.
   # I.e. calling convention cannot be not "pass-by-value"
   arg1.whatever = 1

   # Rebind variables in the local namespace.
   # I.e. calling convention cannot be "pass-by-reference"
   arg1, arg2, arg3 = 1, 2, 3

   # Return rebound variables to achieve the effect of
   # "pass-by-reference":
   return (arg1, arg2, arg3)

# Call the function foobar, and rebind its arguments to its
# return values:

arg1, arg2, arg3 = foobar(arg1, arg2, arg3)