To return a value or not to return a value, that is the question

[lukeedw]

I have a class Vector (representing a 3D Vector). I want to normalize that Vector (to give it a length of 1). From the three possibilities below (or feel free to suggest your own) what would you guys choose?

1. Normalize function that modifies the object:

public void Normalize()

2. Normalize function that returns a modified version of the object leaving the original object untouched.

public Vector Normalize()

3. Do both, modify the original and return that instance.

public Vector Normalize()

The question arises as I want to compare two vectors but I want to try and normalize the second vector within the equality operation:

v1 == v2.Normalize()

I like option 1 as it is simple when just normalizing a vector but stumps me for the problem above.

[Curtis Rutland]

If you're going to be doing things like temporarily normalizing the vector for comparison purposes, I would suggest going with the second option. It's pretty easy to say v2 = v2.Normalize(); if you want to make your changes stick. Strings work that way, so it's not all that unfamiliar.