Question

Good morning,

Suppose I have a class

public class Class
{
    int something;
    int[] otherThing;
}

and I want to make objects of type Class immutable. Suppose also that I have a very frequent operation which creates a new object of type Class,

public Class SomeFunction()
{
    int[] Temp = new int[] { ... };

    return new Class(1, Temp);
}

To avoid creating new objects too often, and since Tempis no longer accessible out of the method, is it too bad to set on the constructor

this.otherThing = Temp;

instead of

otherThing = new uint[Temp.Length];

for (int i = 0; i < Temp.Length; i++)
{
    this.otherThing[i] = Temp[i];
}

?

Thank you very much.

Answer 1

If the constructor that does this is private its fine IMO. Since you know the content of the other array will never change you can directly use it. You could even share one instance of the array between several instances of your class if you want to without causing any problems.

A public constructor directly using a provided array is a bad idea on the other hand. Since that can be used to break immutability.