dynamic classes and duck typing

[Denis Koroskin]

On Tue, 01 Dec 2009 00:00:23 +0300, Walter Bright  
<newshound1 at digitalmars.com> wrote:

> Álvaro Castro-Castilla wrote:
>> It does. Shouldn't this work also?
>>  struct foo {
>>     void opDispatch( string name, T... )( T values ) {     }   }
>>                                                                                                                                         
>> void main( ) {     foo f;
>>     f.bar( 3.14 );
>> }
>
> Declare as:
>
>      void opDispatch(string name, T...)(T values...)
>                                                 ^^^

What? I am using code like Álvaro posted all the time, whereas your syntax  
doesn't even work (according to my test):

void foo(T...)(T values)
{
}

foo(42);

Error: template test.foo(T...) does not match any function template  
declaration
Error: template test.foo(T...) cannot deduce template function from  
argument types !()(int)

I wonder why it works for opDispatch (if it does, as you say).