Understand points, colons, and self in the Lua language

In lua programming, you often encounter definitions and calls to functions, sometimes with dots, sometimes with colons, and here's a simple explanation of the principle. Such as:

Dot call:

-- 点号定义和点号调用:
girl = {money = 200}

function girl.goToMarket(girl ,someMoney)
    girl.money = girl.money - someMoney
end

girl.goToMarket(girl ,100)
print(girl.money)

Reference parameter self:

-- 参数self指向调用者自身(类似于c++里的this 指向当前类)
girl = {money = 200}

function girl.goToMarket(self ,someMoney)
    self.money = self.money - someMoney
end

girl.goToMarket(girl, 100)
print(girl.money)

Colon call:

-- 冒号定义和冒号调用:
girl = {money = 200}

function girl:goToMarket(someMoney)
    self.money = self.money - someMoney
end

girl:goToMarket(100)
print(girl.money)

The colon definition and colon call are actually the same effect as above, omitting the first hidden argument, which self points to the caller itself.

Summary: The colon simply omits the first argument, self, which points to the caller itself, and there is nothing special about it.

Quote blog post: http://www.xuebuyuan.com/1613223.html