c# - Struct extension methods -


with code: 

somevector.fixrounding(); //round vector's values integers if difference 1 epsilon float x = somevector.x; //still getting old value 
public static void fixrounding(this vector3 v) {     if (mathf.approximately(v.x, mathf.round(v.x))) v.x = mathf.round(v.x);     if (mathf.approximately(v.y, mathf.round(v.y))) v.y = mathf.round(v.y);     if (mathf.approximately(v.z, mathf.round(v.z))) v.z = mathf.round(v.z); }

the fixrounding method doesn't change vector's values although mathf.approximately returns true.

this declaration:

public static void fixrounding(this vector3 v)

... means v being passed by value, , it's struct, assuming documentation correct. therefore changes make won't visible caller. need make regular method, , pass v reference:

public static void fixrounding(ref vector3 v)

and call as:

typedeclaringmethod.fixrounding(ref pos);

here's demonstration of extension methods try modify structs passed value failing:

using system;  struct vector3 {     public float x, y, z;      public override string tostring() => $"x={x}; y={y}; z={z}"; }  static class extensions {     public static void doublecomponents(this vector3 v)     {         v.x *= 2;         v.y *= 2;         v.z *= 2;     }      public static void doublecomponentsbyref(ref vector3 v)     {         v.x *= 2;         v.y *= 2;         v.z *= 2;     } }  class test {     static void main()     {         vector3 vec = new vector3 { x = 10, y = 20, z = 30 };         console.writeline(vec); // x=10; y=20; z=30         vec.doublecomponents();         console.writeline(vec); // still x=10; y=20; z=30         extensions.doublecomponentsbyref(ref vec);         console.writeline(vec); // x=20; y=40; z=60     } }

now if vector3 class, second line printed x=20; y=40; z=60... because it's struct, modifying value that's passed doesn't change caller's perspective. passing reference fixes that, hence third line of output.


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