Lua中调用函数使用点号和冒号的区别

TSprite = {
        x = 0,
        y = 0,
    }
    function TSprite.setPosition(x, y)
        TSprite.x = x;
        TSprite.y = y;
    end
   
    TSprite.setPosition(1, 2);
    print("TSprite坐标(" .. TSprite.x .. "," .. TSprite.y .. ")");

TSprite = {
        x = 0,
        y = 0,
    }
    function TSprite.setPosition(x, y)
        TSprite.x = x;
        TSprite.y = y;
    end
   
    TSprite.setPosition(1, 2);
    print("TSprite坐标(" .. TSprite.x .. "," .. TSprite.y .. ")");

TSprite = {
        x = 0,
        y = 0,
    }
    function TSprite:setPosition(x, y)
        self.x = x;
        self.y = y;
    end
    local who = TSprite;
    TSprite = nil;
     
    who:setPosition(1, 2);

 TSprite坐标(1,2)