Suggestion: function template overloading

[Kristian]

On Tue, 29 Aug 2006 21:44:35 +0300, Sean Kelly <sean at f4.ca> wrote:
> Kristian wrote:
>> On Tue, 29 Aug 2006 21:04:53 +0300, Sean Kelly <sean at f4.ca> wrote:
>>
>>> Kristian wrote:
>>>>  It would be very nice if you could overload function templates as  
>>>> you can in C++. Here is what I mean:
>>>>  void f(T)(T val) {...}
>>>>  void f(int val) {...}  //error: conflicts with the template function
>>>>  It would allow you to write special cases for types that need it.
>>>
>>> void f(T)(T val) {}
>>> void f()(int val) {}
>>>
>>>
>>> Sean
>>  Ah, thanks! I missed _that_ one completely... :/
>>  But now I can't get the following to work:
>>  bool equal(T)(T l, T r) {
>>     return l == r;
>> }
>> bool equal()(Foo l, Foo r) {
>>     return l.m_val == r.m_val;
>> }
>>  class Foo {
>>     int m_val = 0;
>> }
>>  class Bar(T) {
>>     this() {
>>         m_val = new T;
>>     }
>>      bool eq(T obj) {
>>         return(equal(m_val, obj));  //error: matches more than one  
>> template, equal(T) and equal()
>>     }
>>      T m_val;
>> }
>>  void main() {
>>     Bar!(Foo) bar = new Bar!(Foo);
>>     Foo foo = new Foo;
>>      printf("%d\n", bar.eq(foo));
>> }
>>  It seems that 'binding' is done when 'Bar' is compiled, not when 'bar'  
>> variable is declared.
>
> In this case, it should choose equal()( Foo ... ) over equal(T)( T ...)  
> because the Foo overload is the most specialized for the supplied  
> parameters.  Unfortunately, implicit template support in DMD is still  
> pretty thin so you're probably running into a compiler limitation rather  
> than a problem with the spec.  Instead of:
>
> equal()( Foo l, Foo r )
>
> try:
>
> equal( T : Foo )( Foo l, Foo r )
>
> and see what happens.  I've found that with a bit of experimentation  
> (and perhaps some wrapper code) you can usually get ITI to work as  
> desired, and simply remove the work-around code as DMD improves.
>
>
> Sean


Ok, thanks again!