Lua class

local _class = {}

function class(super)
    local class_type = {}
    class_type.ctor = false
    class_type.super = super
    class_type.new = function(...)
        local obj = {}
        ---super支持
        obj.super = _class[super]
        do
            local create
            create = function(c, ...)
                if c.super then
                    create(c.super, ...)
                end
                if c.ctor then
                    c.ctor(obj, ...)
                end
            end
            create(class_type, ...)
        end
        setmetatable(obj, { __index=_class[class_type]})
        return obj
    end
    local vtbl = {}
    _class[class_type] = vtbl

    setmetatable(class_type, {__newindex =
                             function(t, k, v)
                                 vtbl[k] = v
                             end
    })

    if super then
        setmetatable(vtbl,{__index =
                           function(t, k)
                               local ret = _class[super][k]
                               vtbl[k] = ret
                               return ret
                           end
        })
    end

    return class_type
end