Re: Multiple return values

fjh@mundook.cs.mu.OZ.AU says...
>... For example, instead of
>
> (x, y) = foo(a, b);
>
>in C you can write
>
> foo(a, b, &x, &y);
>
>and in C++ or Ada you can write
>
> foo(a, b, x, y);
>
>and (at least to a first approximation) this is no less convenient.


In my opinion there is a great difference in readability of the code.
In the multiple-return example you directly see which values are input
to the function and which are output, especially as compared to the
C++ example. In C++, Pascal, Ada, Basic or whatever you need to see
the subprogram declaration to be able to determine what it is doing.


Normally there are three different kinds of parameters. With Ada
terminology: in out and inout (a fourth would be "notused"...:-) Let
me suggest a new notation for these parameter types:


      (out1,out2, ...outn) = (ref1,ref2,...refn).func(in1,in2,...inn)


This syntax would immediately show which values are parameters, return
values and "side-effects". It is also (with a slight change of
semantics) backward compatible with the popular dot-notation for
calling OO methods when we have only one inout parameter.


Comments?


--Jens
[Looks like Perl. -John]


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