Javascript function types and pass by reference?

Unity Engine
,
1

When I put a function reference in an array object, what type should I give it if I want to invoke it? How would I do this?

array3;

Also why does javascript copy string variables, and how can you make it pass by reference?

Ex:
var bla : String = “aaa”
var ar : Array = new Array(“hello”, bla);
ar[1]; // → “aaa”
bla = “bbb”;
ar[1]; // → “aaa”, not “bbb”

2

Not sure if you can cast an object to a function after the fact. If it’s possible, I’d love to know how to do it!

But the following seems to work:

var myfunctions : Function[];
function sum(n1 : float, n2 : float){return n1+n2;}
function subtract(n1 : float, n2 : float){return n1-n2;}
myfunctions = Array(sum, subtract);

function Update () {
	Debug.Log(myfunctions[0](66,33)+" "+myfunctions[1](200,150));
}
3

I figured it out… use ‘as Function’.

function sum(n1 : float, n2 : float){return n1+n2;}
function subtract(n1 : float, n2 : float){return n1-n2;}
var myfunctions = Array(sum, subtract);

function Update () {
	var answer = (myfunctions[0] as Function)(23,19);
	Debug.Log(answer);
}
4

Hey it works, thanks!

Also why does javascript copy string variables, and how can you make it pass by reference?

Ex:
var bla : String = “aaa”
var ar : Array = new Array(“hello”, bla);
ar[1]; // → “aaa”
bla = “bbb”;
ar[1]; // → “aaa”, not “bbb”

5

strings on assignement generate a new string and drops the old.
Strings are never replaced internally unless you work with the buffers themself making, the strings quite a bit slower.

6

Yeah, that makes sense dream.

It’s good to know that you can do that, but is there any direct function variable type that I can use to store functions in objects? Or do i have to leave them as “Object” variables and just cast whenever I want to call them?

7

I guess internally JS wraps them up to Delegates, which represent typesafe and function header safe “method objects”

8

As for the storing functions in variables in order to execute them through the proxy variable, this will surely be of help:

http://forum.unity3d.com/threads/47765-delegates-function-pointers?p=604322&viewfull=1#post604322

As for strings being passed by reference (like a C char string[ ] pointer), rather than being assigned, I don’t really know, if if I had to guess I’d say it’s not possible at least without digging deeper into the .Net String class.

HTH!

  • jmpp