Overloading funtion templates.

[vit via Digitalmars-d-learn]

On Thursday, 29 June 2017 at 06:40:04 UTC, Balagopal Komarath 
wrote:
> On Wednesday, 28 June 2017 at 12:19:31 UTC, vit wrote:
>> auto foo(alias F, T)(T x)
>> {
>>     return x.foo(&F);
>> }
>
> With this definition foo!((x) => x+1)(3); doesn't work. Is 
> there a way to solve this?

You don´t need overload templates:



import std.traits : isCallable;

auto foo(alias F, T)(T x)
if(isCallable!F)			//this line is optional
{
     return F(x);
}


int g(int x) { return x; }

struct G{
	int i;
	this(int i){
		this.i = i;
	}
	int opCall(int x){return x*i;}	//int operator()(int x)
}

void main(){
     foo!g(3);
	foo!((int x) => x*2)(3);
	auto g2 = G(4);
	foo!g2(3);
	foo!(G(5))(3);
}