Re: Lua registry, environment, and threads.
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- Subject: Re: Lua registry, environment, and threads.
- From: "Juris Kalnins" <juris@...>
- Date: 2010年1月12日 11:00:34 +0200
On 2010年1月12日 08:23:28 +0200, Juris Kalnins <juris@mt.lv> wrote
do
a=1
do
a=2
g() -- access to a gives 2
end
-- a == 1
end
ugh, correcting myself. what I wrote mixes up definitions and assignments,
I should have written:
do a=1
do dynamic a=2
g() -- access to a gives 2
end -- a == 1
end
where 'dynamic' is like 'local' in perl :)
There are already many ways to do it right now. Usually code has to pass
around some context as an
extra argument, and the above looks like:
do ctx.a=1
do
local prev_a = ctx.a
ctx.a = 2
g(ctx)
ctx.a = prev_a
end
end
You can even "smuggle" 'ctx' through functions that are not aware of it
(e.g. gsub), by capturing it as
upvalue.
When writing parser or GUI code, there is a lot of such 'ctx' passing and
value saving.
Dynamic scoping makes writing such code very natural.
- References:
- Re: Lua registry, environment, and threads., Christian Tellefsen
- Re: Lua registry, environment, and threads., Roberto Ierusalimschy
- Re: Lua registry, environment, and threads., Mark Hamburg
- Re: Lua registry, environment, and threads., Patrick Donnelly
- Re: Lua registry, environment, and threads., Roberto Ierusalimschy
- Re: Lua registry, environment, and threads., Leo Razoumov
- Re: Lua registry, environment, and threads., Petite Abeille
- Re: Lua registry, environment, and threads., Paul Moore
- Re: Lua registry, environment, and threads., Petite Abeille
- Re: Lua registry, environment, and threads., Juris Kalnins
- Re: Lua registry, environment, and threads., Sean Conner
- Re: Lua registry, environment, and threads., Juris Kalnins