Re: Where are returned values stored? (follow up to yesterday's question)

[Simon Wright <simon@pushface.org>]

James Alan Farrell <anonymous@anonymous.com> writes:

> Now its my understanding that when variables are declared like this,
> they are added onto the stack, then when the function returns, they
> are popped off again, along with the regular stack frame.  So the
> stuff returned goes away.
> 
> But, the calling function will need use of that data.  So it cannot go
> away.  
> 
> So how does that work?  Where is the data placed so that it does not
> go away, and how long will it be there so it (or rather pointers to
> it) can be passed around to other functions?

The simple answer is that it returns a copy of the data, just like
simple variables ..

   int foo()
   {
     // stuff
     {
       int res;
       // stuff
       return res;
     }
     return 3;
   }

There may be a more complicated, implementation-dependent answer
involving secondary stacks, but I see no reason in the language why
you need the concept of pointer in this context. And, however it
works, it will be stack-based, so the data will go away at some point
as the stack is popped.

-- 
Simon Wright                               100% Ada, no bugs.