Is all this Invarient **** er... stuff, premature optimisation?

[Hans W. Uhlig]

e-t172 wrote:
> Lionello Lunesu a écrit :
>>
>> "Walter Bright" <newshound1 at digitalmars.com> wrote in message 
>> news:48169E90.6050700 at digitalmars.com...
>>> Me Here wrote:
>>>> Janice Caron wrote:
>>>>> Functions don't overload on return value.
>>>> They don't? Why not? Seems like a pretty obvious step to me.
>>>
>>> Type inference in D is done "bottom up". Doing overloading based on 
>>> function return type is "top down". Trying to get both schemes to 
>>> coexist is a hard problem.
>>
>> But a function's result can be overloaded using "out", so why can't it 
>> be overloaded using the return value?
>>
>> Can't the compiler treat a return value as an implicit out argument?
> 
> Consider this:
> 
> int foo();
> float foo();
> 
> void bar(int a);
> void bar(float a);
> 
> Then this:
> 
> void main()
> {
>     bar(foo());
> }
> 
> There is an obvious problem here.

One of two things, make an assumption as to which is called by which has 
the higher priority(based on precision or type). Or throw a compiler 
error if no cast is made.

Overload Ambiguity, Cast Must be made when both return overload and 
parameter overload types are ambigious.