Lua编程form

local form = {}
-- form to produce the target with super functional table and integrating multi-interface implement feature
function form.build(tag, super)
    super = super or form
    local target = {_tag = tag, _super = super}
    return setmetatable(target, form._meta())
end

-- specification on the target
function form.on(target, spec)
    local handler = {}
    function handler.function(target, spec)
        return function ( ... )
            return spec(target, ...)
        end
    end
    function handler.table(target, spec)
        local tar = {}
        for k,v in pairs(spec) do
            if type(v) == ‘function‘ then
                tar[k] = function ( ... )
                    spec[k](target, ...)
                end
            else
                tar[k] = v
            end
        end
        return tar
    end
    local handler_spec = handler[type(spec)]
    if handler_spec then
        print(target._tag..‘[‘..prop..‘] target binding form produced‘)
    end
    return handler_spec and handler_spec(target, spec)
end

--[[
function form:spec(prop, target) end
local p1 -- protocol specification
local p2 -- protocol specification
local px -- any interface spec
-- Future init style
local Future = 
    form.build(‘Future‘):spec(‘proto_xxx‘, p1)
                        :spec(‘proto_xx2‘, p2)
                        :spec(px)
-- protocol usecase, assume implemented on target ‘Future‘
-- assume there p1:funcall defined
Future:spec(‘proto_xxx‘).funcall()
-- assume there px:funcall defined
Future:funcall()
--]]
function form:spec(prop, target)
    local handler = {}
    function handler.string(self, prop, target)
        if target ~= nil then
            print(self._tag..‘[‘..prop..‘] setter/getter produced‘)
            local property = ‘_‘..prop
            local function prop_(self, target)
                if target ~= nil then
                    self[property] = target
                    return self
                end
                return self[property]
            end
            prop_(self, target)[prop] = prop_
        end
        return form.on(self, self[prop](self))
    end
    function handler.table(self, prop)
        local target = prop
        local interface = self._interface or {}
        if  self._interface == nil then
            self._interface = interface
        end
        table.insert(interface, target)
        if type(target._tag)==‘string‘ then
            print(self._tag..‘ interface[‘..target._tag..‘] specified‘)
        end
        return self
    end
    local handler_prop = handler[type(prop)]
    return handler_prop and handler_prop(self, prop, target)
end

function form._meta()
    local meta = {}
    function meta.__index(target, key)
        local v = target._super[key]
        if v == nil then
            local interface = target._interface or {}
            for i=1, #interface do
                v = interface[i][key]
                if v ~= nil then return v end
            end
        end
        return v
    end
    return meta
end

return form

local p1 -- protocol specification
local p2 -- protocol specification
local px -- any interface spec
-- Future init style
local Future = 
    form.build(‘Future‘):spec(‘proto_xxx‘, p1)
                        :spec(‘proto_xx2‘, p2)
                        :spec(px)
-- protocol usecase, assume implemented on target ‘Future‘
-- assume there p1:funcall defined
Future:spec(‘proto_xxx‘).funcall()
-- assume there px:funcall defined
Future:funcall()
-- using property getter
Future:proto_xx2()==p2