Re: 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) {}
}