Bug Report LuaJIT 2.0.3 __ipairs metatable method behaviour differ from Lua __ipairs metatable method behaviour.
- From: Eric Man <meric.au@xxxxxxxxx>
- To: luajit@xxxxxxxxxxxxx
- Date: Fri, 13 Feb 2015 20:18:12 +1100
Hello,
I was trying to hook into __ipairs to build a ipairs-compatible linked list
type in lua.
I found the ipairs behaviour is different in LuaJIT and Lua with the same
code.
I don't know if this is an intentional optimisation made by LuaJIT to "fix"
the "self" up value when calculating __ipairs.
I'm not sure if it is specific to ipairs or references upvalues in general.
You can see the code below:
➜ Desktop lua ipairstest.lua
1 1
2 2
3 3
➜ Desktop luajit ipairstest.lua
1 1
2 table: 0x0004a5c8
➜ Desktop lua -v
Lua 5.3.0 Copyright (C) 1994-2015 Lua.org, PUC-Rio
➜ Desktop luajit -v
LuaJIT 2.0.3 -- Copyright (C) 2005-2014 Mike Pall. http://luajit.org/
➜ Desktop cat ipairstest.lua
list = {
__ipairs = function(self)
local i = 0
return function()
if self then
local obj = self[1]
self = self[2]
i = i + 1
return i, obj
end
end
end
}
local alist =
setmetatable({1,
setmetatable({2,
setmetatable({3, nil}, list)},
list)},
list)
for i, v in ipairs(alist) do
print(i, v)
end
Best Regards,
Eric
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