RE: copying userdata objects?
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- Subject: RE: copying userdata objects?
- From: Nick Trout <Nick.Trout@...>
- Date: Tue, 2 Apr 2002 10:42:49 +0100
> I have added a couple of 3D object types (vector, matrix,
> quaternion) to Lua as userdata objects. The default behavior of a
> statement like:
>
> vector2 = vector1
>
> is to set both values to reference the same userdata object. But I
> would like my math objects to behave like the simple data types, in
> that assignment makes a *copy* of the object, and changing vector2
> would have no effect on vector1. Is there an easy way to accomplish
> this in Lua?
I'm not sure this is a good idea as you may be ambiguities, or it wont be
clear whats happening in the code. It may also be pretty inefficient. I dont
think you'll *always* want to copy a vector? Perhaps you should use a copy
constructor to explicitly state whats going on?
eg.
vector1 = vector() -- constructor
vector1 = vector{1,2,3} -- constructor
vector2 = vector(vector1) -- copy constructor
vector3 = vector1 -- reference
Where you use operators you can create new vectors:
eg. vector1 = vector2 + vector3
Regards,
Nick