Модуль:Yesno

Module:Yesno provides a consistent interface for processing boolean or boolean-style string input. While Lua allows the true and false boolean values, wikicode templates can only express boolean values through strings such as "yes", "no", etc. This module processes these kinds of strings and turns them into boolean input for Lua to process. It also returns nil values as nil, to allow for distinctions between nil and false. The module also accepts other Lua structures as input, i.e. booleans, numbers, tables, and functions. If it is passed input that it does not recognise as boolean or nil, it is possible to specify a default value to return.

---

-- Imported from: https://en.wikipedia.org/wiki/Module:Yesno

-- Function allowing for consistent treatment of boolean-like wikitext input.
-- It works similarly to the template {{yesno}}.

return function (val, default)
    -- If your wiki uses non-ascii characters for any of "yes", "no", etc., you
    -- should replace "val:lower()" with "mw.ustring.lower(val)" in the
    -- following line.
    val = type(val) == 'string' and val:lower() or val
    if val == nil then
        return nil
    elseif val == true
            or val == 'yes'
            or val == 'y'
            or val == 'true'
            or val == 't'
            or val == 'on'
            or val == 'ja'
            or tonumber(val) == 1
    then
        return true
    elseif val == false
            or val == 'no'
            or val == 'n'
            or val == 'false'
            or val == 'f'
            or val == 'off'
            or val == 'nein'
            or tonumber(val) == 0
    then
        return false
    else
        return default
    end
end