電暈：嘗試索引全局“自我”（nil值）

Question

我有一個創建太空飛船的類，我希望它包含一個使飛船撞到特定牆壁時將其自身移走的函數。 但是，運行下面的代碼，我得到以下錯誤：

...xenosShip.lua:16:
attempt to index global 'self' (a nil value)
stack traceback:
[C]:?
...xenosShip.lua:16: in function ...xenosShip.lua:14> ?:in function <?:218

>

我想念什么？

local xenosShip = {}

-- XENOS SHIP COLLISION
local function xenosColl(event)
    if (event.phase == "began" and event.other.myName == "bottomWall") then
    self:removeSelf()
    end
end


-- XENOS SHIP
function xenosShip.new()

    local newXenosShip=display.newSprite( alShipSheet, alShipSeqData )
    newXenosShip:play()
    newXenosShip.x=300
    newXenosShip.y=70
    newXenosShip.myName = "newXenosShip"
    physics.addBody(newXenosShip,"dynamic", {density = 1.0, friction = 0.3, bounce = 1})
    newXenosShip:applyForce(50,2500,newXenosShip.x,newXenosShip.y)
    newXenosShip:addEventListener("collision", xenosColl)

end

return xenosShip

Answer 1

您可以這樣做， self不是顯示對象，或者它沒有對顯示對象的引用，因此object:removeSelf()存在錯誤

local function xenosColl(event)
    if (event.phase == "began" and event.other.myName == "bottomWall") then
        event.target:removeSelf()
    end
end

如果您想使用自我 ，可以這樣做。 因此，自我現在正在引用newXenosShip 。

function xenosShip.new()

    local newXenosShip=display.newSprite( alShipSheet, alShipSeqData )
    newXenosShip:play()
    newXenosShip.x=300
    newXenosShip.y=70
    newXenosShip.myName = "newXenosShip"
    physics.addBody(newXenosShip,"dynamic", {density = 1.0, friction = 0.3, bounce = 1})
    newXenosShip:applyForce(50,2500,newXenosShip.x,newXenosShip.y)
    newXenosShip.collision = function(self,event)
        if (event.phase == "began" and event.other.myName == "bottomWall") then
                self:removeSelf()
        end
    end

    newXenosShip:addEventListener("collision")
end

Answer 2

我最近遇到了相同的錯誤消息； 對我來說，這是一個簡單的語法錯誤，而不是

 playerInstance:resetTargetPosition()

我曾經用過

 playerInstance.resetTargetPosition()

（請注意.而不是: ）