Lua OOP沒有找到變量

Question

我正在嘗試在Lua中進行OOP，但這並不是讓我在checkInput {}方法中更改vel_y值。 任何想法我怎么能讓這個工作？ 順便說一句，我正在使用Love2D來輸入這些東西。

Player = {x = 100, y = 20, vel_x = 0, vel_y = 0}
function Player:new(o, x, y, vel_x, vel_y)
    o = o or {}   -- create object if user does not provide one
    setmetatable(o, self)
    self.__index = self
    length = 0
    return o
end

function Player:getX()
    return self.x
end

function Player:getY()
    return self.y
end

function Player:update( dt )
    --update velocity
    self.x = self.x + self.vel_x
    self.y = self.y + self.vel_y
    checkInput()

end

function checkInput( dt )

    if love.keyboard.isDown("w") and length < 5 then --press the right arrow key to push the ball to the right
        length = length + 1
        self.vel_y = 5
        print("bruhddddddddddddddddddddddd")
    elseif love.keyboard.isDown("a") then

    elseif love.keyboard.isDown("s") then

    elseif love.keyboard.isDown("d") then

  end
end

Answer 1

我假設您的系統調用player：update（）會觸發嗎？ 如果是這樣，您應該將self和dt傳遞給checkInput

function Player:update( dt )
    --update velocity
    self.x = self.x + self.vel_x
    self.y = self.y + self.vel_y
    checkInput(self, dt) --<--
end
...

function checkInput( self, dt )
...

如果你將checkInput定義為local （當然在Player:update之前），這可能類似於private方法。

Player = {x = 100, y = 20, vel_x = 0, vel_y = 0} do
Player.__index = self -- we can do this only once

function Player:new(o, x, y, vel_x, vel_y)
  o = setmetatable(o or {}, self) -- create object if user does not provide one
  -- init o here
  return o
end

function Player:getX() end

function Player:getY() end

-- Private method
local function checkInput(self, dt) end

function Player:update( dt )
  ...
  checkInput(self, dt) -- call private method
end

end -- end clsss defenitioin