[Python-3000] in-out parameters

[Jim Jewett]

On 5/4/06, Rudy Rudolph <rudyrudolph at excite.com> wrote:
>
> // C++ does not distinguish between in-out and out parameters.
> // call them
> int x = 2; foo(x); // x is now 7
>

It is important to avoid this obfuscation.

C's &addr is slightly better, but still pretty error prone with
collections, like a string or array.


> Python:
> def foo(paramWrapper):
>     paramWrapper[0] += 5
>

or use named fields of an object

    def foo(data):
         dataobject.param3 +=5

or return a tuple if you need a multiple-values-return

    x=foo(x)
    val1, val2, val3 = foo(val4, val1, val5)

At best, adding an out parameter is the equivalent of adding in-place
operators

    a += 1
vs
    a = a + 1


-jJ
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