opDispatch and compile time parameters

[Steven Schveighoffer via Digitalmars-d]

On 11/14/15 12:18 AM, Jakob Ovrum wrote:
> On Saturday, 14 November 2015 at 04:10:59 UTC, Steven Schveighoffer wrote:
>> Is it me, or is this a bug?
>>
>> struct Foo
>> {
>>    template opDispatch(string s) {
>>       // if you uncomment this, it compiles
>>       //void opDispatch() {}
>>       void opDispatch(T...)() {}
>>    }
>> }
>>
>> void main()
>> {
>>    Foo f;
>>    f.blue!char(); // Error: no property 'blue' for type 'Foo'
>> }
>
> Usually you should explicitly instantiate opDispatch to see the real
> error message(s) that prevented opDispatch from being used, but in this
> case I can't find a way to do that. `f.opDispatch!("blue")!char()` is
> syntactically invalid, and aliasing doesn't work either: `alias t =
> f.opDispatch!"blue"; t!char(); // Error: need `this` for opDispatch`. I
> wonder what the real error is.
>

It appears that you can't directly access the eponymous member, this 
doesn't work:

f.opDispatch!("blue").opDispatch!(char)();

Error: no property 'opDispatch' for type 'void'

Perhaps that fact that it *works* when you have the non-template version 
as the first member is the bug ;)

In any case, I have used Jack Applegame's improved version, and it works 
beautifully!

-Steve