Re: Virtual methods on stack objects

[Ali Çehreli via Digitalmars-d-learn]

On 5/11/22 13:06, Marvin Hannott wrote:

> I appreciate the answer, don't much like the "solutions".

Me neither. :)

> It's not so much about copying

Great!

> scoped class objects should have value semantics.

std.typecons.scoped does exactly that:

  https://dlang.org/phobos/std_typecons.html#scoped

import std.stdio;
import std.typecons;

interface Animal {
  string sing();
}

class Cat : Animal {
  this() {
    writeln("Hi!");
  }

  ~this() {
    writeln("Bye!");
  }

  string sing() {
    return "mew";
  }
}

void foo(Animal animal) {
  writeln(animal.sing());
}

void bar() {
  auto cat = scoped!Cat();
  foo(cat);
}

void main() {
  bar();
}

The output:

Hi!
mew
Bye!

Ali