Custom "comparison for equality" in Lua ?

[Didier Guillion <didier@...>]

Hi,

In Lua 4.0 I read it is already possible to write a custom "ordered
comparison" function 
through the "lt".

Is it a way to write a custom "equal" function ?

Let's take an example :
Let's say I want to implement a "complex number" data type.
It is made of a table, with two indexes "r" and "i"

How can I let the lua interpreter make :

a.r=1
a.i=2

b.r=1
b.i=2

if a==b then print("equality") end

run as expected  (i.e. print "equality") ?

Please consider I do not need a trick to implement complex numbers only.
It is just an 
example. 

The object type I need actually to implement is much more complicated,
with its own 
tag and tag methods. I know how to compare such objects for equality, but
I could not 
find a way to trap the comparison, except by rewriting the
"LuaO_EqualObj" in the Lua 
sources...

Thanks in advance for any advice or comment.
Didier Guillion
Myriad Software
France
mailto:didier@myriad-online.com