shouting versus dotting

[Denis Koroskin]

On Mon, 06 Oct 2008 14:56:43 +0400, Michel Fortin  
<michel.fortin at michelf.com> wrote:

> On 2008-10-05 22:23:16 -0400, Michel Fortin <michel.fortin at michelf.com>  
> said:
>
>> Well, not so sure about that: I'm pretty sure it's needed for  
>> disambiguation too. Let's say you have:
>>  	void foo(int x)();
>> 	void foo(T)(T x);
>>  	foo(5);
>>  Is foo(5) a the same as foo!(5), or does it call foo!(int).foo(5) ?  
>> Under the current rules, it's the second (you can write foo!(5) to call  
>> the first). If you allow templates to be instanciated without the "!",  
>> then I guess both will match and you'll have ambiguity.
>>  If you could avoid having sets of parameters, one for the function and  
>> one for the template, then you could get rid of the "!" in a snap...
>
> Or... we could just disallow having both at the same time, just like you  
> can't have two functions with the same arguments. A call to foo(5) would  
> be ambigous in the above situation, plain and simple. Is this reasonable?
>
> We could still disambiguate using:
>
> 	foo!(5);
>
> and:
>
> 	foo(int)(5);
>
> In this context, the ! becomes the "force this to be template arguments"  
> operator, or the "do not deduce template arguments, I'll provide them"  
> operator.
>
> Or we could just forget ! completely and leave the first one impossible  
> to disambiguate.
>
> Which makes me think that it's sad we can't write the second as:
>
> 	foo(int, 5);
>
> I'd be much nicer to the eye.
>

If we don't omit parenthesises, the ambiguity goes away:

foo()(5)
foo(5)()