Re: Overloading funtion templates.

[Balagopal Komarath via Digitalmars-d-learn]

On Friday, 30 June 2017 at 04:51:23 UTC, vit wrote:

import std.traits : isCallable;

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



Thanks. That works.

Re: 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();
}


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);
}

Re: Overloading funtion templates.

[vit via Digitalmars-d-learn]

On Wednesday, 28 June 2017 at 11:49:57 UTC, Balagopal Komarath 
wrote:
Shouldn't the compiler be able to resolve foo!g(3) to the first 
template foo?


import std.stdio;
import std.algorithm;
import std.range;

auto foo(F, T)(T x)
{
return x.foo(F);
}

auto foo(F, T)(T x, F f)
{
return f(x);
}

int g(int x) { return x; }

void main()
{
foo(3, ); // 2nd foo
foo!g(3);   // error
}

I get the error message.

onlineapp.d(20): Error: template onlineapp.foo cannot deduce 
function from argument types !(g)(int), candidates are:

onlineapp.d(5): onlineapp.foo(F, T)(T x)
onlineapp.d(10):onlineapp.foo(F, T)(T x, F f)


symbol 'g' isn't type.

auto foo(alias F, T)(T x)
{
return x.foo();
}