Module:Sandbox/Artoria2e5/Fallback: Difference between revisions

Revision as of 14:20, 13 October 2016

Revision as of 04:49, 16 October 2016

Line 6:

local oldArgsMeta = getmetatable(args) or {}

local newArgsMeta = {}

-- Forget about thread-safety.

local referencedKeys = {} -- dataType:Set/hashtable-impl

-- Start the new metatable as a copy of the old metatable.

for k, v in ipairs(oldArgsMeta) do

newArgsMeta[k] = v

end

-- Change the __index metamethod to our implementation.

-- See https://www.lua.org/pil/13.4.1.html.

newArgsMeta.__index = function (t, k)

-- My friend, why are you here again?

-- Try the old metamethod first.

if referencedKeys[k] then

-- Thanks to closures, this whole oldArgsMeta object will stay.

-- You have to be drunk. Go home.

if oldArgsMeta.__index ~= nil then

return valnil

local val = oldArgsMeta.__index(t, k)

end

if val ~= nil then

referencedKeys[k] = true

return val

end

-- Try the old metamethod first.

end

-- Thanks to closures, this whole oldArgsMeta object will stay.

if oldArgsMeta.__index ~= nil then

local val = oldArgsMeta.__index(t, k)

if val ~= nil then

referencedKeys = {}

return val

end

end

-- Now try use the aliases given.

for _, v in ipairs(arg_aliases[k] or {}) do

-- If a working value is found, use it.

-- Note: mw-argument-specific empty str chk.

if t[v] ~= nil and t[v] ~= '' then

if t[v] ~= nil returnand t[v] ~= '' then

referencedKeys = {}

end

return t[v]

end

end

return nil