C# Extension method change current value

Question

Is there a way to change the Unity Vector3 struct value inside an Extension Method in this way?

Vector3 myVector = new Vector(3.5f, 0.7f, 2f);
myVector.Floor(); // it should be (3f, 0f, 2f) instead it's (3.5f, 0.7f, 2f) still

it only works in this way:

myVector = myVector.Floor(); // now it's (3f, 0f, 2f)

Extension Code:

public static void Floor(this Vector3 vector)
{
    vector.Set(Mathf.Floor(vector.x), Mathf.Floor(vector.y), Mathf.Floor(vector.z));
}

or

public static void Floor(this Vector3 vector)
{
    vector.x = Mathf.Floor(vector.x);
    vector.y = Mathf.Floor(vector.y);
    vector.z = Mathf.Floor(vector.z);
}

Vector3 seems to be a struct have a look at: https://stackoverflow.com/questions/13049/whats-the-difference-between-struct-and-class-in-net — Rand Random, Oct 02 '22 at 14:50

ggeorge · Accepted Answer · 2022-10-02T15:07:20.610

6

Your extension method should be like this:

public static void Floor(ref this Vector3 vector)
{
    vector.x = Mathf.Floor(vector.x);
    vector.y = Mathf.Floor(vector.y);
    vector.z = Mathf.Floor(vector.z);
}

because struct is value type

Here's an example: https://dotnetfiddle.net/NItg0O

edited Oct 02 '22 at 15:07

answered Oct 02 '22 at 14:50

ggeorge

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1

can a static extension actually have the ref keyword? – Rand Random Oct 02 '22 at 14:52
1

yes i reproduced it in my end and works properly – ggeorge Oct 02 '22 at 14:54
Are you sure that's possible? Did you try this? – Julian Oct 02 '22 at 14:55
Which C# version? – Julian Oct 02 '22 at 14:57
The version i used is c# 10.0 – ggeorge Oct 02 '22 at 15:01
This works in C# 9.0 yet – ProtoTyPus Oct 02 '22 at 21:37
I hate mutable structs and so should you. Doing `Floor(this Vector3 vector) => new Vector3(Math.Floor(vector.x), ...` would the way to go to avoid the pitfalls of mutability with structs. – John Alexiou Oct 02 '22 at 22:28

C# Extension method change current value

1 Answers1