[5.0] trying to auto init a nil field on first ref...
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- Subject: [5.0] trying to auto init a nil field on first ref...
- From: Ando Sonenblick <ando@...>
- Date: 2003年12月11日 20:15:22 -0800
Gang,
I have a table that represents a rectangle. Normally it'd be set up
like:
r = {
top = 0
left = 0
right = 100
bottom = 100
}
so that if I then:
r.top = r.top + 10
print(r.top)
I get "10"
What I'd like to do however is have the four fields, if nil when
referenced, auto default to zero. I've been trying to get this with
__index and __newindex in a metatable, but I can't seem to find a way.
In other words, say I do this:
r = {}
r.top = r.top + 10
print(r.top)
I want want lua to successfully realize that r.top is nil and instead
of throwing an error, auto init r.top to zero, add 10 to it, and then
print the result
Is this possible? I'm staring to confuse myself now more than gain any
clarity....
Thx mucho,
Ando
-----------------------
Ando Sonenblick
SpriTec Software
www.spritec.com