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Could we implement it in lua‘s C
source code ？
I hava the same need as Ricky, and
now thinking a method
to solve it in lua's source code.
2010-03-25
bravefly
发件人： Pierre-Yves_Gérardy
发送时间： 2010-03-25 17:34:35
收件人： Lua list
抄送：
主题： Re: Cleaning up specific lua
scripts
I'm glad I could help :-)
You could add a collectgarbage() call at the end of cleanLevel().
That said, the setfenv() solution is probably more elegant and more robust.
local protectMT = {__newindex=error}
local levelMT = {index=_G}
local MTindex
local function protectTable(tbl,index)
for k,v in pairs(tbl) do
if
type(v)==table and
getmetatable(v) ~= protectMT -- prevents from getting lost in
then -- circular references.
index[k]={getmetatable(v),{})
protectTable(v,index[k][2])
setmetatable(v,protectMT)
end
end
end
local function unprotectTable(tbl,index)
for k,v in pairs(tbl) do
if type(v)=="table" then
setmetatable(v,index[k][1])
unprotectTable(v,index[k][2])
end
end
end
local loadLevel = function(levelpath)
local levelenv=setmetatable({},levelMT)
local levelcode=loadfile(levelpath)
setfenv(levelcode,levelenv)
protectTable(_G,MTindex)
-- it's now impossible to add or modify any global, or any
subtable of a global.
local ret = levelcode()
unprotectTable(_G,MTindex)
return ret
end
To give back the control from a level, return from it's main chunk
(e.g., return true on level completion and false on death).
local success = loadlevel(level1)
collectgarbage()
if success then
loadNextLevel()
else
restartLevel()
end
The above code is not tested and may contain syntax or semantic
errors, but you get the idea :-)
Cheers,
-- Pierre-Yves
On Thu, Mar 25, 2010 at 09:14, Ricky Haggett <ricky@honeyslug.com> wrote:
> Pierre,
>
> This is a simpler and more elegant version of what I implemented yesterday afternoon, which also seemed to do the job, albeit with more fuss.. I'm definitely going to upgrade to your code today..
>
> Thanks,
>
> Ricky
>
> -----Original Message-----
> From: lua-bounces@bazar2.conectiva.com.br [mailto:lua-bounces@bazar2.conectiva.com.br] On Behalf Of Pierre-Yves Gérardy
> Sent: 24 March 2010 19:27
> To: Lua list
> Subject: Re: Cleaning up specific lua scripts
>
> On Wed, Mar 24, 2010 at 12:30, Ricky Haggett <ricky@honeyslug.com> wrote:
>> Yep, we could store a table of all of the functions / tables within a
>> specific level script, but it would be awkward for the designers to
>> maintain, and a potential source of error...
>
> You could also do it the other way around:
> after you've loaded your global scripts do
>
> globals={}
>
> function cleanLevel()
> for k,_ in pairs(_G) do
> if not globals[k] then _G[k] = nil
> end
> end
>
> for k,_ in pairs(_G) do
> globals[k]=true
> end
>
> globals will index all globals present at that point (including itself
> and cleanlevel() ), and cleanLevel() will only delete the globals not
> referenced there. Case solved :-)
>
> Cheers,
> -- Pierre-Yves
>
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