Re: How to hook a lua variable accessing
[
Date Prev][
Date Next][
Thread Prev][
Thread Next]
[
Date Index]
[
Thread Index]
- Subject: Re: How to hook a lua variable accessing
- From: steve donovan <steve.j.donovan@...>
- Date: 2013年1月23日 10:23:15 +0200
On Wed, Jan 23, 2013 at 10:10 AM, Huang, Baiyan
<Baiyan.Huang@morganstanley.com> wrote:
> Then I want to remove this global variable, but I want to give a buffer time
> for our user to off board, so I stage the change and firstly it will emit an
> warning if user is using this global variable. Is there a way to achieve
> this without using LuaMacros?
Sure, but you have to attach a metatable to _G, that tracks
__newindex. For this to fire on GLOBAL_VARIABLE this variable must
not be in _G already, so __index is defined to look it up.
Something like this:
local global_variable = 'boo'
local function message(writing)
print 'you are still using GLOBAL_VARIABLE'
end
setmetatable(_G,{
__index = function (t, k)
if k == 'GLOBAL_VARIABLE' then
message(false)
return global_variable
end
end;
__newindex = function(t,k,v)
if k == 'GLOBAL_VARIABLE' then
message(true)
global_variable = v
end
end;
})
Easy to generalize for a whole bunch of 'globals' that you want to deprecate.
steve d.