Partial ordering of constructors with type parameters

[monarch_dodra via Digitalmars-d-learn]

On Wednesday, 23 April 2014 at 16:44:37 UTC, Charles McAnany 
wrote:
> Friends,
>
> I have a class that needs two constructors:
>
> class Foo{
>     this(int x){}
>     this(T)(T x) if(!is(T == int)){}
> }
> void main(){}
>
> But this does not compile because the two constructors conflict:
>
> buggy.d(3): Error: template buggy.Foo.__ctor(T)(T x) if (!is(T 
> == int)) conflicts with constructor buggy.Foo.this at buggy.d(2)
>
> Of course, I can just have one constructor that doesn't have 
> the constraint and then use a static if to redirect to a 
> private method, but that seems clunky to me. (not to mention it 
> would complicate the documentation.)
>
> Any ideas?
>
> Cheers,
> Charles McAnany.

Update your compiler. What version are you on? This was resolved 
in the 2.064 release. You don't even need the "if(!is(T == 
int))", since non-template takes precendence.

//----
class Foo{
     this(int x){}
     this(T)(T x) {}
}
void main()
{
     auto a = new Foo(5);
}
//----

If you can't update your compiler, an alternative is to make your 
non-template version an actual template:

class Foo{
     this(T : int)(T x){}
     this(T)(T x) {}
}