Re: Multiple return values

Ray Dillinger <bear@sonic.net> wrote:


> As far as I've gotten in thinking about it is to try to detect whether
> the calling code wants (will actually use) one return value or more
> (most of the time I figure it'll only want one) and compile separate
> versions of the function; one which returns a single value (in
> registers or on the stack) and one which returns more than a single
> value (likewise).


One approach is to have the caller tell the callee how many and/or which
return values it actually cares about. The caller knows this, but the
callee doesn't. This can be utilized for overloading (a la Ada), or for
run-time testing.


A good example of this is a bignum quotient+remainder. If you tell the
routine in advance whether you want the quotient, the remainder, or both,
then the subroutine doesn't have to waste time generating the unwanted
results.
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