Re: Lua 5.2: Can you explain this behaviour?
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- Subject: Re: Lua 5.2: Can you explain this behaviour?
- From: Dirk Laurie <dpl@...>
- Date: 2011年9月15日 10:15:54 +0200
On Thu, Sep 15, 2011 at 08:36:09AM +0200, Eric Man wrote:
>
> If you run the code snippet, it'll print "= a<a<". I'd have thought it would be "= a<<.>a<<.>>".
>
> If you toggle line 4 off, though, it will print "= a<<.>a<<.>>" as expected.
>
...
> local function test(bool)
> local w, t
> if bool
> --or true --- toggle this line
> then
> t = "a"
> w = function (s) t = t .. tostring(s) end
> _ENV.w = w
> else
> t = "."
> end
>
Since 'w' never appears outside 'loadstring', the local 'w' is
irrelevant, and you can get rid of the '_ENV'. (Once you do that,
Lua 5.1 also runs the snippet.)
The above code simplifies to
local function test (bool)
local t
if bool then
t = "a"
function w(s) t = t .. tostring(s) end
else
t = "."
end
Whereas the code below, since the 'or true' means the condition
always holds
> local function test(bool)
> local w, t
> if bool
> or true --- toggle this line
> then
> t = "a"
> w = function (s) t = t .. tostring(s) end
> _ENV.w = w
> else
> t = "."
> end
>
simplifies to
local function test (bool)
local t = "a"
function w(s) t = t .. tostring(s) end
Dirk