Arseny Kapoulkine :

Uh, blog software ate all my braces. Trying again:

Q: Why don’t you define a Vector4 ctor? like that:

I tried that but I prefer the above for multiple reasons:
1. It means that I need to create a constructor that does Vector3 and Vector2, which means that Vector3 and Vector4 need to be defined (but not declared) at that point.
2. Not all data that is delivered is my custom Vector class, sometimes (when using an external library for physics for example) you have a different type.
3. In general it’s less work

Of course, the last reason was the most important reason. The results are virtually the same, although yours look nicer, but those can always be added at a later stage.

Q: Why don’t you define a Vector4 ctor? like that:

template struct Vector4
{
template explicit Vector4(const Vector3& v, float w = 1) { ... } /* or without default value if you like */
};


template struct Vector4
{
template explicit Vector4(const Vector3& v, float w = 1) { … } /* or without default value if you like */
};