Re: Backport of Lua 5.2 "in" scoping
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- Subject: Re: Backport of Lua 5.2 "in" scoping
- From: David Kastrup <dak@...>
- Date: 2010年1月08日 18:10:33 +0100
Matthew Wild <mwild1@gmail.com> writes:
> I'm interested whether the patch is correct. From the other thread I
> thought I understood that functions would stop using the environment
> they were defined in by default, and instead the environment they are
> called in. Such that this simple example would fail (due to lack of
> print in env):
>
> function sayhello() print("Hello") end
> env = { sayhello = sayhello }
> in env do sayhello() end
>
> Am I wrong in my understanding?
I think so. Since no local "print" exists at the time of compilation,
this is resolved at compile time to the equivalent of
_G.print("Hello")
Now if you change _G.print, this will affect sayhello's operation I
should think. But "in" does not touch _G AFAICT, merely sets it aside
for the purpose of resolving symbols. Already resolved symbols will
retain their resolution (though not necessarily their value).
That's my understanding.
--
David Kastrup
- References:
- Lua registry, environment, and threads., Christian Tellefsen
- Re: Lua registry, environment, and threads., Roberto Ierusalimschy
- 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., Enrico Colombini
- Re: Lua registry, environment, and threads., Roberto Ierusalimschy
- Backport of Lua 5.2 "in" scoping (was Re: Lua registry, environment, and threads.), Mike Pall
- Re: Backport of Lua 5.2 "in" scoping (was Re: Lua registry, environment, and threads.), Matthew Wild