Haxe macro to set null to calling instance? - macros

Question

Is there a way of setting a null to calling instance as a result of some "macro-function-call"?
Like so:
class A {
// ...
macro function DestroyItself() {
// ...
}
}
var a:A = new A();
// ...
a.DestroyItself();
trace(a); // "null"

Answer 1

Yep:
macro public function destroy(self:Expr) {
return macro $self = null;
}
// ...
a.destroy();
In non-static macro functions first Expr argument is a ref to caller instance.

Answer 2

Once approach would be to create generic tools to null any instance.
package ;
class Tools
{
/**
* Simply assigns null to the instance
* See more at: http://code.haxe.org/category/macros/generating-code-in-a-macro.html
*
* #param instance - Any
* #return haxe.macro.Expr
*/
public static macro function nullMe(instance : haxe.macro.Expr.ExprOf<Dynamic>) : haxe.macro.Expr
{
return macro {
${instance} = null;
};
}
}
This use the using Tools; to generically null any instance, but I would not recommend this. I'd use the per-class approach.
Main.hx
package ;
class Main {
static function main() {
// Construct
var instance = new SomeClass();
// Destroy
instance.destroy();
// Trace null
trace(instance);
}
}
SomeClass.hx
package ;
class SomeClass
{
public function new()
{
trace("Hello from SomeClass!");
}
private function preDestroy()
{
trace("The end is nigh!");
}
public macro function destroy(self : haxe.macro.Expr) : haxe.macro.Expr
{
return macro {
#:privateAccess ${self}.preDestroy();
${self} = null;
};
}
}
Compiled JS
// Generated by Haxe 3.4.2
(function () { "use strict";
var Main = function() { };
Main.main = function() {
var instance = new SomeClass();
instance.preDestroy();
instance = null;
console.log(instance);
};
var SomeClass = function() {
console.log("Hello from SomeClass!");
};
SomeClass.prototype = {
preDestroy: function() {
console.log("The end is nigh!");
}
};
Main.main();
})();