Clone a class instance

1

GIven this example

class Cat {
    public var name:String;
public function say_hello(){
trace("hello fron $name");
};
    public function new() {
        
    }
}

class Main {
    public static function main() {
        var c=new Cat();
        c.name="miki";
        var c2=c;
        c2.name="mouse";
        trace(c.name);
        trace(c2.name);
    }
}

Output

Main.hx:14: mouse
Main.hx:15: mouse

How could i clone the object instead of creating a reference (like [].copy()) or like clone in rust

2

Reflect.copy only copies filed, but not the methods (in JS target)

3

If cloning copies structure of the data, whereas copy does the same and copies the data, then you can do cloning via

var c2 = Type.createEmptyInstance(Type.getClass(c))
4

Thanks

But I want to keep the current fields, and only change the few fields I want

5

Then you need to copy, not to clone. Here is full sample showing how can be done versus anonymous object copy (Reflect.copy)

class Cat {
    public var name:String;
    public function say_hello(){
        trace("hello from "+name);
    };

    public function new() {
        
    }
}

class Cat2 extends Cat {
}

class Main {

    public static function copyClass<T>(c:T):T {
	var cls:Class<T> = Type.getClass(c);
    var inst:T = Type.createEmptyInstance(cls);
	var fields = Type.getInstanceFields(cls);
	for (field in fields) {
		var val:Dynamic = Reflect.field(c,field);
		if ( ! Reflect.isFunction(val) ) {
			Reflect.setField(inst,field,val);
		}
	}
	return inst;
    }

    public static function main() {
        var c=new Cat();
        c.name="miki";
	var c2 = copyClass(c);
	trace("old c2.name="+c2.name);
        c2.name="mouse";
	var c3 = new Cat2();
	c3.name = "miki2";
	var c4 = copyClass(c3);
       	c.say_hello();
        c2.say_hello();
        c3.say_hello();
        c4.say_hello();
	var o = { name:"", say_hello:(o)->trace("hello from "+o.name) }
	o.name="miki";
	var o2 = Reflect.copy(o);
	o2.name="mouse";
	o.say_hello(o);
	o.say_hello(o2);
    }
}
1 Like
6

Great. I would say its beneficial to add it to the stdlib