Metaprogramming work around

["Erèbe"]

On Tuesday, 17 April 2012 at 12:46:28 UTC, Kenji Hara wrote:
> On Tuesday, 17 April 2012 at 12:04:44 UTC, Erèbe wrote:
> [snip]
>>
>> There is something I still don't understand :
>>
>> mixin template Foo( T... )
>> {
>> //Code here
>> }
>>
>> mixin Foo!( "Hello", "Word" ); <---- Good
>
> T is TemplateTypeParameter, and matches any kind of template 
> arguments - types, values, and symbols. The both arguments 
> "Hello" and "World" are values, so you can bind them with T.
>
> http://dlang.org/template.html#TemplateTupleParameter
>
>> --------------------------------------------
>>
>> "mixin template Foo( A, T... )
>> {
>> //code here
>> }
>>
>> mixin Foo!( "Hello", "Word" ); <--- Fail !
>> mixin Foo!( string, "Word" ); <---- Good
>> --------------------------------------------
>
> 'A' is TemplateTypeParameter, and it matches only types. In the 
> first instantiation of Foo, A doesn't match with the value 
> "hello".
> In the second instantiation, string is type, and T matches with 
> it.
>
> http://dlang.org/template.html#TemplateTypeParameter
>
>> mixin template Foo( alias A, T... )
>> {
>> //code here
>> }
>>
>> mixin Foo!( "Hello", "world" ); <--- Good
>> mixin Foo!( string, "world" ); <--- Fail !
>>
>> ---------------------------------------------
>
> 'alias A' is TemplateAliasParameter, and it matches both 
> symbols and values.
> Then A matches with the value "Hello", but doesn't with the 
> type string.
> (string is an aliased name of immutable(char)[], and it is 
> built-in array type.)
>
> http://dlang.org/template.html#TemplateAliasParameter
>
> Kenji Hara


Thanks a lot Kenji Hara,
I have a better understanding of it now !