正确使用 lua 表/类

Question

我正在尝试在 lua 中使用 class 行为，其中有一艘船有两个其他类 pos 和 vector 但我无法让它像我假设的那样工作

Point = {x=0, y=0}
function Point:new(p)
  p = p or {}
  return p
end

Ship =
{
  pos = {Point:new{x=0,y=0}},
  vector = {Point:new{x=0,y=0}} -- I thought this would be sufficient for access being available for vector
}

-- create new ship class
function Ship:new(pos)
  p = p or {}
  p.pos = pos
  p.vector = Point:new{x=0,y=0} -- I need to do this or accessing vector will crash (The problem)
  return p
end

-- Create new ship...
plrShip = Ship:new{}
plrShip.pos.x = 300
plrShip.pos.y = 300

如果有人知道如何使上述代码更干净/更好，我将不胜感激

Answer 1

您可以使用元表来设置默认字段。 （我对您尝试做的事情做了一些假设。如果这对您不起作用，请对您的问题进行一些说明。）

local Point = {x=0, y=0}
Point.__index = Point
function Point:new(p)
  p = p or {}
  setmetatable(p, self)
  return p
end

-- create new ship class
local Ship = {}
Ship.__index = Ship
function Ship:new(pos)
  setmetatable(pos, Point)
  local p = {pos = pos, vector = Point:new()}
  setmetatable(p, self)
  return p
end

-- Create new ship...
local plrShip = Ship:new{}
plrShip.pos.x = 300
plrShip.pos.y = 300

Answer 2

我找到了解决方案，它仍然不完美，但只有我开始工作的是这个修改过的代码：

Ship =
{
  pos = Point:new{x=0,y=0},
  vector = Point:new{x=0,y=0}
}

function Ship:new()
  p = p or {}
  p.pos = self.pos
  p.vector = self.vector
  return p
end

plrShip = Ship:new()
plrShip.pos.x = 300
plrShip.pos.y = 300