Re: Recipe: setfenv with Lua 5.2.0 work3

[Henk Boom <henk@...>]

On 21 May 2010 11:55, François Perrad <francois.perrad@gadz.org> wrote:

I rewrite setfenv as follow :

local function setfenv (level, M)
    level = level + 1
    local func = debug.getinfo(level, 'f').func
    local up = 1
    while true do
        local name = debug.getupvalue(func, up)
        if name == '_ENV' then
            debug.setupvalue(func, up, M)
            return
        end
        if name == nil then
            break
        end
        up = up + 1
    end
    _G.setfenv(level, M) -- Lua 5.1
end

François

Does this run into the problem that Roberto points out with shared upvalues?

local print = print

x = 1

function foo ()

  local function a()

    print(x)

  end

  local function b()

    print(x)

  end

  return a, b

end

a, b = foo()

setfenv(a, {x=2})

b()

Does that print 1 or 2?

    henk