Why Does Initialising Built-In Array of Classes Require Constructor?

Questions & Answers
1

Say I have the following short script:

#pragma strict

class myArrayInfo
{
	var name:String;
}

static var myArray:myArrayInfo[];

function Start()
{
	myArray=new myArrayInfo[3];
	myArray[0].name="Random name 1";
	myArray[1].name="The answer to the ultimate question of life, the universe, and everything is...";
	myArray[2].name="...42.";
}

I would expect that to work, but I get NullReferenceException: Object reference not set to an instance of an object at line 13, where I attempt to set index 0 of the array.

So I tried doing this:

#pragma strict

class myArrayInfo
{
	var name:String;
	function myArrayInfo(){}
}

static var myArray:myArrayInfo[];

function Start()
{
	myArray=new myArrayInfo[3];
	myArray[0]=new myArrayInfo();
	myArray[1]=new myArrayInfo();
	myArray[2]=new myArrayInfo();
	myArray[0].name="Random name 1";
	myArray[1].name="The answer to the ultimate question of life, the universe, and everything is...";
	myArray[2].name="...42.";
}

And this works. But why?! Why is it necessary to make it run an empty function (the constructor) to be assigned a value? The constructor clearly isn’t doing anything, unless I’m completely misunderstanding how constructors work.

2

The constructor primarily gets a memory location for a new object. It optionally also initializes the object.

When creating an array of objects the array is initialized with all null references ( 0x0000000 ). You need to call the class’s constructor to get a valid memory location and therefore an object. Primitive types work a little differently in that you don’t need to call a constructor for it to be in memory since they are value types.

An example: If you had

var info : myArrayInfo;
info.name = "Name";

it would return an error since the constructor has not been called.