This module returns a function that will convert various values to false or true. It can be used to interpret boolean template parameters, if Module:parameters is not being used.
-- Function allowing for consistent treatment of boolean-like wikitext input.
-- It works similarly to the template {{yesno}}.
local lower = string.lower
local type = type
return function (val, default)
if val == nil then
return nil
end
val = type(val) == "string" and lower(val) or val
return (
val == true or val == "true" or val == 1 or val == "1" or
val == "yes" or val == "y" or val == "t" or val == "on"
) and true or not (
val == false or val == "false" or val == 0 or val == "0" or
val == "no" or val == "n" or val == "f" or val == "off"
) and default
end