opDispatch/template get this

[John Chapman via Digitalmars-d-learn]

On Monday, 3 April 2017 at 21:49:07 UTC, Inquie wrote:
> I am using opDispatch to wrap function calls
>
> Error: 'this' is only defined in non-static member functions, 
> not opDispatch!"foo"
>
> class X
> {
>     auto localfoo() { return 3; }
>     template opDispatch(string name, Args...)
>     {
>         static if (name == `foo`) { alias opDispatch = () { 
> return this.localfoo();
>     };
> }
>
>
> which doesn't work because of this
>
> I tried
>
> template opDispatch(string name, this _this, Args...)
> {
> 	static if (name == `foo`) { alias opDispatch = () { return 
> _this.localfoo(); };
> }
>
> but that doesn't work either ;/
>
> I call it like
>
> auto y = x.foo();
>
> but foo isn't found
>
>
> https://dpaste.dzfl.pl/bf31f535340f
>
>
>
> class X
> {
>     auto localfoo() { return 3; }
>     auto localfoo2(int x) { return x; }
>     template opDispatch(string name, Args...)
>     {
>         static if (name == `foo`)
> 		{
> 			alias opDispatch = () { return this.localfoo(); };
> 		}
> 		static if (name == `bar`)
> 		{
> 			alias opDispatch = () { return this.localfoo2(); }; // need 
> to be able to pass Args properly here
> 		}
> 	}
> }
>
> void main()
> {
> 	auto x = new X();
> 	auto z = x.localfoo();
> 	auto y = x.foo();
> 	auto q = x.bar();
> }

Make opDispatch a templated function and forward with 
__traits(getMember, this, "foo") or a mixin.

class X {

   auto localfoo() { return 3; }
   auto localfoo2(int x) { return x; }

   auto opDispatch(string name, Args...)(auto ref Args args) {
     static if (name == "foo") return __traits(getMember, this, 
"localfoo")(args);
     else static if (name == "bar") mixin("return 
localfoo2(args);");
   }

}