Code shared from run.dlang.io.

main.d

import std.stdio;
import std.datetime;
import std.stdint;
import std.conv;

class Writer
{
    this(void delegate() del)
    {
        _del = del;
    }
    
    auto apply()
    {
        _del();
    }
    void delegate() _del;
}


int main()
{
    
    int[] l = [1, 2, 3, 4];
    
    void doStuff() {writeln(l);}
    
    auto w = new Writer(&doStuff);
    
    w.apply;
    
    l ~= [3, 4];
    
    w.apply;
   
    return 0;
}