Make the code shorter in Unity3D with Vector3 and float value in 1 axis - unity3d

Question

This is my code:
transform.localPosition = new Vector3(transform.localPosition.x, Mathf.PingPong(Time.time * movementSpeed, movementRange), transform.localPosition.z);
Can you help me to short it?
Like
transform.localPosition = Vector3.up * Mathf.PingPong(Time.time * movementSpeed, movementRange)
I am constantly encountering a Vector3 abbreviation of this form, but can't write this code any better

Answer 1

Perfect use-case for Extension Methods
public static class Vector3Extensions {
public static Vector3 SetY(this Vector3 vector, float y) {
//This works as-is because structs, such as Vector_ in Unity, are pass-by-value
vector.y = y;
return vector;
}
}
Usage:
//You have to assign the result of the method because, again, pass-by-value...
//..So the vector that was modified inside the method is a different object from the original
transform.localPosition = transform.localPosition.SetY(Mathf.PingPong(Time.time * movementSpeed, movementRange));
Your second example is functionally different from the first. In it, the X and Z will be zero instead of inheriting the original transform's values. If your intention is that, then your example's code is already pretty much as small as it gets, without another extension method to the Transform class, ie transform.SetLocalPositionY(y).
If you need inheritance of the X and Z values, AND using SetY would still be too verose to your liking, then use a Transform Extension Method as I said above:
public static class TransformExtensions {
public static void SetLocalPositionY(this Transform transform, float y) {
transform.localPosition = transform.localPosition.SetY(y);
}
}
Usage:
//Assignment not needed in this case, as transform is a class...
//..and assignment of localPosition is handled inside the extension method.
transform.SetLocalPositionY(Mathf.PingPong(Time.time * movementSpeed, movementRange));
There is a slight performance cost to extensions methods for struct types, due to the pass-by-value nature of structs. Which are the types being used in this case. But it's negligible in this case specifically, and should be negligible for all structs in general, if you are using structs correctly.
On pass-by-reference types, there should be no performance cost any different to any standard static method modifying the data.
Note that the operation does not need to be inline, and if you're willing to spread it across a few lines, you can use the same principle of the extension method, of modifying a cached clone of the original vector and then (re)assigning it back to the transform, to achieve this with shorter lines and without the extra struct instance from passing as parameter and then returning (one instance creation instead of two):
var localPos = transform.localPosition; //Creates temp/cached instance
localPos.y = Mathf.PingPong(Time.time * movementSpeed, movementRange); //Modification
transform.localPosition = localPos; //(Re)Assignment.
But with exception to cases requiring extreme performance, the extension will be fine. In fact, anything short of a case verified in the debugger, doing it this way just for the performance concern is going to be premature-optimization.