It looks alright to me, but you'll incur some overhead every time you
call lib.foo as _G.foo. If this is a problem and you've got memory to
spare, you could do this:
local mt = setmetatable(_G, {})
local lib = _G.lib
function mt:__index(key)
if [key is one of a list of possible keys] then
local f = lib[key]
self[key] = function()
print('Warning! Deprecated usage of function ' .. key)
return f(...)
end
return self[key]
else
return nil
end
end
This method ends up caching the lookups.
-Rob
On 2010年12月09日 18:21:12 +0100
Francesco Santini <rincewind@tin.it> wrote:
> Dear list,
>
> I am working on a project where Lua is embedded inside a larger C
> environment. In a previous version, I had registered some C functions
> as Lua globals (through lua_register), thus polluting the global
> scope.
>
> Now I would like to do things right, so I registered the same
> functions as members of a table (say "lib"), so that they are called
> as lib.myfun() instead of just myfun().
>
> However, I would like to keep some support for the "global"
> convention, as I cannot expect all the scripts to be ported to the
> new convention immediately. But at the same time I would like to
> print a warning whenever a function is called as global before
> falling beck to lib.xxx.
>
> I implemented a version that adds a metatable to _G that defines the
> __index metamethod more or less like the following:
>
> mt = {}
>
> mt.__index = function(table, key)
> if [key is one of a list of possible keys] then
> print("Warning! Deprecated usage")
> return lib[key]
> else
> return nil
> end
> end
>
> setmetatable(_G, mt)
>
>
> I tested it and it seems to work, but I am a bit worried about adding
> such a metamethod to the global environment. Is it a good idea? Is
> there some loophole that I might fall into in some cases? Is there a
> better way of achieving my goal?
>
> Thanks!
>
> Cheers,
>
> Francesco
>
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