struct Foo {

  int payload;

  this(int i)

  {

    this.payload = i;

  }

  this(ref return scope Foo that)

  {

    this = that; //cC = copyConstructor

    logger ~= format("cC(%s)", that.payload);

  }

  Foo opUnary(string op)()

  if(op == "++") {

    ++this.payload;

    return this;

  }

​

  int getter()

  {

    return payload;

  }

  alias getter this;

}

​

import std.stdio, std.format;

string logger;

​

void main() {

  Foo one = Foo(1), two = 2;

  int[] arr = [one, two, Foo(3)];

  auto three = ++two;/*

  two.writeln(": 0x", &two.payload);//*/

  //arr.writeln;/*

  foreach(ref i; arr) {

    i.writeln(": 0x", &i);

  }//*/

  writeln("0x", &three.payload);

  logger.writeln;

} // end with the logger! 

/*

Let be the structure Foo that wraps an int pointer. Let's setup Foo in 3 different ways:

1. Foo one = Foo(1);

2. Foo two = 2;

3. [ Foo(3) ];

​

Pretty clean, right? So why it's not run copy-constructor in 3? Also, when we write to the screen with writeln(), why four times copy-constructor are running?

 */

​