Re: Recipe: setfenv with Lua 5.2.0 work3

[Roberto Ierusalimschy <roberto@...>]

> 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