Lua OOP 未找到变量

Question

我正在尝试在 Lua 中执行 OOP，但它不允许我更改 checkInput{} 方法中的 vel_y 值。我有什么想法可以让它发挥作用吗？顺便说一句，我正在使用 Love2D 作为输入内容。

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

我假设你的系统调用先是 player:update()？如果是这样，您应该将 self 和 dt 传递给 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 )
...

如果你定义checkInput为local（当然在Player:update之前）这可能类似于私有方法。

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

Lua OOP 未找到变量

Lua OOP not finding variables

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