Do pure functions solve the "return const" problems?

[Christopher Wright]

Janice Caron wrote:
> On 05/04/2008, Christopher Wright <dhasenan at gmail.com> wrote:
>> Still, there shouldn't be any difference between
>> out parameters and return values.
> 
> I think there should. Suppose f is declared:
> 
>     pure int f(out int n);
> 
> Now consider the expression:
> 
>     f(x) + f(x)
> 
> See the problem?

That might be an argument for removing out parameters -- it looks like 
f(x) + f(x) is the same as 2 * f(x). The compiler could tell the 
difference, so there's no problem on that side. It could basically 
rewrite the pretty f(x) + f(x) as the mess you recommended.

You could require the 'out' qualifier at the call site to make it clear 
what's going on when you're reading the code. That's probably a better 
solution.