lua中使用table实现类和继承

--因为只有当读写不存在的域时，才会触发__index和__newindex

classA = {className = "classA",name="classAInst"}

function classA:new(newobject)

    newobject = newobject or {}

    setmetatable(newobject, {__index = self})--当在newobject找不到key对应的value时，就到self(即classA)类中查找

    return newobject

end

function inherit(p)

    local newclass = {className = "classB",parent = p}

    setmetatable(newclass,{__index=p})--当在newclass中找不到key对应的value时，就到p类中查找

    function newclass:new(newobject)

        newobject = newobject or {}

        setmetatable(newobject,{__index = newclass})--当在newobject找不到key对应的value时，就到newclass类中查找

        return newobject

    end

    return newclass

end

testA = classA:new()

print("testA ==> ",testA.className)

print("testA ==> ",testA.name)

testB = inherit(classA):new({name = "testB"})

print("testB ==> ",testB.className)

print("testB ==> ",testB.name)

testC = inherit(classA):new()

print("testC ==> ",testC.className)

print("testC ==> ",testC.name)

testD = inherit(testB):new()

print("testD ==> ",testD.className)

print("testD ==> ",testD.name)

testA ==> classA
testA ==> classAInst
testB ==> classB
testB ==> testB
testC ==> classB
testC ==> classAInst
testD ==> classB
testD ==> testB