Cool. Now, since setfenv is totally possible, I like the _ENV :)
Here are my implementations of setfenv and getfenv:
setfenv = setfenv or function(f, t)
f = (type(f) == 'function' and f or debug.getinfo(f + 1, 'f').func)
local name
local up = 0
repeat
up = up + 1
name = debug.getupvalue(f, up)
until name == '_ENV' or name == nil
if name then
debug.upvaluejoin(f, up, function() return name end, 1) --
use unique upvalue
debug.setupvalue(f, up, t)
end
end
getfenv = getfenv or function(f)
f = (type(f) == 'function' and f or debug.getinfo(f + 1, 'f').func)
local name, val
local up = 0
repeat
up = up + 1
name, val = debug.getupvalue(f, up)
until name == '_ENV' or name == nil
return val
end
On 16.06.2010 18:46, Roberto Ierusalimschy wrote:
I thought upvaluejoin can only join upvalues. How can it be used to
break the link?
function breaklink (f, upidx)
local a
local function dummy () return a end
debug.upvaluejoin(f, upidx, dummy, 1)
end
The call 'breaklink(f,n)' will make the n-th upvalue from 'f' point to
a fresh upvalue (refering to variable 'a'), not shared with any other
function.
-- Roberto
