(Yet another) Accessing array in another script - ref or copy?

Questions & Answers
1

I know how to access an array from another script. I’m pretty sure I know the answer to this, but want to be sure: am I accessing a copy of that array, or a reference to it? What if that array is changed?

Ex (both scripts on same object):

   class ClassA {
      Color32[] colors;
      void Start {
       colors = new Colors32[640*480];
      }
      Update() {
       // change colors
       foreach (c in colors)
         c = RandomColor();
       // or REALLY change colors
       colors = someTexture.GetPixels();
     }
   }

now in another class I want to get at the CURRENT ‘colors’ array.

class ClassB {
 ClassA A; // will set with Inspector
 void Update() {
   Analyze (A.colors); // the CURRENT color array from object A
 }
}

So, what will A.colors be in classB’s Update? Ideally what I want is a reference to that array so I can read/write it, no matter what it happens to be, like a reference or C pointer-to-pointer.

2

This code shouldn’t do anything (at least not in C#), because c will become a temporary variable, so assigning a value to this temporary variable means it’ll be lost.

foreach (c in colors)
    c = RandomColor();

You are accessing a reference to the Color32 array. The contents are not copied by accessing it.

So, what will A.colors be in classB’s Update?

A.colors will probably reference a new array each time as I suspect someTexture.GetPixels() return a new array each call. The copying doesn’t happen when you access A.colors – it’ll just be a reference and the contents will be shared across different accesses. However, it’s ClassA.Update that set a new reference to colors each update, and I am pretty sure each call to GetPixels generate a new array.

So the net effect is that you’ll probably see different references each time you access ClassA.colors because it’s reassigned every frame.