fork download

copy

import std.stdio;
import std.traits;
 
template DelegateToFunction(DG, string ID1=__FILE__, int ID2=__LINE__) {
    alias ParameterTypeTuple!DG PT;
    alias ReturnType!DG RT;
    void* thisp;
    RT function(PT) funcp;
    RT function(PT) DelegateToFunction(DG dg) {
        thisp = dg.ptr;
        funcp = dg.funcptr;
        return &WrapFunction;
    }
    RT WrapFunction(PT p) {
        RT delegate(PT) dg;
        dg.funcptr = funcp;
        dg.ptr = thisp;
        return dg(p);
    }
}
 
void main()
{
    int a = 1;
    int delegate(int, int) d = (int x, int y){ return a += x + y; };
    int function(int, int) f = DelegateToFunction(d);
    writeln(f(20, 300));
    writeln(a);
}

prog.d(4): Error: template prog.DelegateToFunction(DG,string ID1 = __FILE__,int ID2 = __LINE__) is not a function template
prog.d(26): Error: template prog.DelegateToFunction(DG,string ID1 = __FILE__,int ID2 = __LINE__) cannot deduce template function from argument types !()(int delegate(int, int))
prog.d(26): Error: cannot implicitly convert expression ((DelegateToFunction(DG,string ID1 = __FILE__,int ID2 = __LINE__))(d)) of type int to int function(int, int)

Standard output is empty