Написано однажды, работает неважно.

mixin template foo() {
    int y;
}

void fn() {
    mixin foo;
    y = 25;
}

import dlangui.core.signals;

interface SomeInterface {
    bool someMethod(string s, int n);
}
class Foo : SomeInterface {
	override bool someMethod(string s, int n) {
		writeln("someMethod called ", s, ", ", n);
		return n > 10; // can return value
	}
}

// Listener! can hold arbitrary number of connected slots

// declare using list of return value and parameter types
Listener!(bool, string, n) signal1;

Foo f = new Foo();
// when signal is defined as type list, you can use delegate
signal1 = bool delegate(string s, int n) { writeln("inside delegate - ", s, n); return false; }
// or method reference
signal1 = &f.someMethod;

// declare using interface with single method
Listener!SomeInterface signal2;
// you still can use any delegate
signal2 = bool delegate(string s, int n) { writeln("inside delegate - ", s, n); return false; }
// but for class method which overrides interface method, you can use simple syntax
signal2 = f; // it will automatically take &f.someMethod


// call listener(s) either by opcall or explicit emit
signal1("text", 1);
signal1.emit("text", 2);
signal2.emit("text", 3);

// check if any slit is connected
if (signal1.assigned)
	writeln("has listeners");

// Signal! can hold arbitrary number of connected slots

// declare using list of return value and parameter types
Signal!(bool, string, n) signal3;

// add listeners via connect call
signal3.connect(bool delegate(string, int) { return false; });
// or via ~= operator
signal3 ~= bool delegate(string, int) { return false; };

// declare using interface with single method
Signal!SomeInterface signal4;

// you can connect several slots to signal
signal4 ~= f;
signal4 ~= bool delegate(string, int) { return true; }

// calling of listeners of Signal! is similar to Listener!
// using opCall
bool res = signal4("blah", 5);
// call listeners using emit
bool res = signal4.emit("blah", 5);

// you can disconnect individual slots
// using disconnect()
signal4.disconnect(f);
// or -= operator
signal4 -= f;