如何在lua类中编写私有函数
我试图用私有函数编写lua“类”,如下所示:如何在lua类中编写私有函数,lua,Lua,我试图用私有函数编写lua“类”,如下所示: local myTable = {} function myTable.func() private() end local function private() print(":O") end return myTable 假设我需要“myTable”,然后运行myTable.func()我会得到一个错误,该错误表示“private”未定义 我找到了两种解决方法: 1) 将“private”函数移到“func”之前 2) 在
local myTable = {}
function myTable.func()
private()
end
local function private()
print(":O")
end
return myTable
假设我需要“myTable”,然后运行myTable.func()我会得到一个错误,该错误表示“private”未定义
我找到了两种解决方法:
1) 将“private”函数移到“func”之前
2) 在“func”之前定义“local private”,并将private的签名更改为“function private”
但是我不太清楚他们为什么工作,以及哪种是最常见的方式,很高兴有人能帮我理解,泰:)
哪一种是常见的方式
这两种方法都是可取的。第二种方法是在两个函数相互调用的情况下需要的,这两个函数都需要是本地的,而不是在一个表中
您可以始终使用第二种样式,从而保持一致性,尽管它的可读性可能不如您需要在代码中的其他位置查看函数是否是本地的
然而,为了可读性和更短的代码,我将使用第一种方法,这样我就不需要对本地函数进行单独的“声明”
我不太明白他们为什么工作
原始代码无法工作的原因是由于局部变量作用域。
从lua参考手册:
Lua是一种词汇范围的语言局部变量的范围
从声明后的第一个语句开始,持续到
最内层块的最后一个非void语句,包括
声明
因此,在原始代码中,变量private
仅在定义行之后定义为函数。代码失败是因为您试图在该行之前的代码中使用它
这些方法之所以有效,是因为它们都将局部变量范围移动到使用变量的代码上方
您可能需要阅读参考手册中有关局部变量和范围的内容:
- 首先:在您的代码片段中,我不清楚“类”在哪里,因为
myTable
只是一个对象。如果你把它放在一个模块中并且需要它
它,你就得到了一个对象
你可以这样做:
local function MyTable() -- constructor
local function private()
print(":O")
end
return {
func = function()
private()
end
}
end
local m = MyTable()
m.func()
local function Bezier(x1,y1,x2,y2,x3,y3)
--Private
local inf = 1/0
local x1 = x1
local y1 = y1
local x2 = x2
local y2 = y2
local x3 = x3
local y3 = y3
local maxY = y1 > y2 and (y1 > y3 and y1 or y3) or y2 > y3 and y2 or y3
local minY = y1 < y2 and (y1 < y3 and y1 or y3) or y2 < y3 and y2 or y3
local maxX = x1 > x2 and (x1 > x3 and x1 or x3) or x2 > x3 and x2 or x3
local minX = x1 < x2 and (x1 < x3 and x1 or x3) or x2 < x3 and x2 or x3
local xc = (x3 - 2*x2 + x1)
local xb = 2*(x2 - x1)
local yc = (y3 - 2*y2 + y1)
local yb = 2*(y2 - y1)
--Public
local self = {}
--Render
self.render = function(resolution)
local path = {}
local num = 1
for index=0, 1, 1/resolution do
path[num] = {(1-index)^2*x1+2*(1-index)*index*x2+index^2*x3, (1-index)^2*y1+2*(1-index)*index*y2+index^2*y3}
num = num + 1
end
return path
end
--Point
function self.point(index)
return {(1-index)^2*x1+2*(1-index)*index*x2+index^2*x3, (1-index)^2*y1+2*(1-index)*index*y2+index^2*y3}
end
--Get x of patricular y
function self.getX(y)
if y > maxY or y < minY then
return
end
local a = y1 - y
if a == 0 then
return
end
local b = yb
local c = yc
local discriminant = (b^2 - 4*a*c )
if discriminant < 0 then
return
else
local aByTwo = 2*a
if discriminant == 0 then
local index1 = -b/aByTwo
if 0 < index1 and index1 < 1 then
print("=====",y,1,maxY,minY)
return (1-index1)^2*x1+2*(1-index1)*index1*x2+index1^2*x3
end
else
local theSQRT = math.sqrt(discriminant)
local index1, index2 = (-b -theSQRT)/aByTwo, (-b +theSQRT)/aByTwo
if 0 < index1 and index1 < 1 then
if 0 < index2 and index2 < 1 then
print("=====",y,2,maxY,minY)
return (1-index1)^2*x1+2*(1-index1)*index1*x2+index1^2*x3, (1-index2)^2*x1+2*(1-index2)*index2*x2+index2^2*x3
else
print("=====",y,1,maxY,minY)
return (1-index1)^2*x1+2*(1-index1)*index1*x2+index1^2*x3
end
elseif 0 < index2 and index2 < 1 then
print("=====",y,1,maxY,minY)
return (1-index2)^2*x1+2*(1-index2)*index2*x2+index2^2*x3
end
end
end
end
--Get y of patricular x
function self.getY(x)
if x > maxX or x < minX then
return
end
if maxX == minX and x == minX then
return minY, maxY
end
local index1, index2, buffer1, buffer2
local a = (x1 - x)
if a == 0 then
return
end
local b = xb
local c = xc
local discriminant = b^2 - 4*a*c
if discriminant < 0 then
return
else
local aByTwo = 2*a
local theSQRT = math.sqrt(discriminant)
if discriminant == 0 then
local index1 = -b/aByTwo
return (1-index1)^2*y1+2*(1-index1)*index1*y2+index1^2*y3
else
local index1, index2 = (-b - theSQRT)/aByTwo, (-b + theSQRT)/aByTwo
return (1-index1)^2*y1+2*(1-index1)*index1*y2+index1^2*y3, (1-index2)^2*y1+2*(1-index2)*index2*y2+index2^2*y3
end
end
end
--Scanline render
function self.scanRender()
local path = {}
local counter = 1
local fX, sX
local a = (y3 - 2*y2 + y1)
local b = 2*(y2 - y1)
for i=minY, maxY do
fX, sX = self.getX(i,a,b)
if fX then
path[counter] = fX
path[counter+1] = i
counter = counter + 2
if sX then
path[counter] = sX
path[counter+1] = i
counter = counter + 2
end
end
end
return path
end
--More efficient
--Self
return self
end
这可能不是Lua中执行OOP的常用方法,但这里的
private
显然是。。好。。私有。您基本上需要这样的东西:
local function MyTable() -- constructor
local function private()
print(":O")
end
return {
func = function()
private()
end
}
end
local m = MyTable()
m.func()
local function Bezier(x1,y1,x2,y2,x3,y3)
--Private
local inf = 1/0
local x1 = x1
local y1 = y1
local x2 = x2
local y2 = y2
local x3 = x3
local y3 = y3
local maxY = y1 > y2 and (y1 > y3 and y1 or y3) or y2 > y3 and y2 or y3
local minY = y1 < y2 and (y1 < y3 and y1 or y3) or y2 < y3 and y2 or y3
local maxX = x1 > x2 and (x1 > x3 and x1 or x3) or x2 > x3 and x2 or x3
local minX = x1 < x2 and (x1 < x3 and x1 or x3) or x2 < x3 and x2 or x3
local xc = (x3 - 2*x2 + x1)
local xb = 2*(x2 - x1)
local yc = (y3 - 2*y2 + y1)
local yb = 2*(y2 - y1)
--Public
local self = {}
--Render
self.render = function(resolution)
local path = {}
local num = 1
for index=0, 1, 1/resolution do
path[num] = {(1-index)^2*x1+2*(1-index)*index*x2+index^2*x3, (1-index)^2*y1+2*(1-index)*index*y2+index^2*y3}
num = num + 1
end
return path
end
--Point
function self.point(index)
return {(1-index)^2*x1+2*(1-index)*index*x2+index^2*x3, (1-index)^2*y1+2*(1-index)*index*y2+index^2*y3}
end
--Get x of patricular y
function self.getX(y)
if y > maxY or y < minY then
return
end
local a = y1 - y
if a == 0 then
return
end
local b = yb
local c = yc
local discriminant = (b^2 - 4*a*c )
if discriminant < 0 then
return
else
local aByTwo = 2*a
if discriminant == 0 then
local index1 = -b/aByTwo
if 0 < index1 and index1 < 1 then
print("=====",y,1,maxY,minY)
return (1-index1)^2*x1+2*(1-index1)*index1*x2+index1^2*x3
end
else
local theSQRT = math.sqrt(discriminant)
local index1, index2 = (-b -theSQRT)/aByTwo, (-b +theSQRT)/aByTwo
if 0 < index1 and index1 < 1 then
if 0 < index2 and index2 < 1 then
print("=====",y,2,maxY,minY)
return (1-index1)^2*x1+2*(1-index1)*index1*x2+index1^2*x3, (1-index2)^2*x1+2*(1-index2)*index2*x2+index2^2*x3
else
print("=====",y,1,maxY,minY)
return (1-index1)^2*x1+2*(1-index1)*index1*x2+index1^2*x3
end
elseif 0 < index2 and index2 < 1 then
print("=====",y,1,maxY,minY)
return (1-index2)^2*x1+2*(1-index2)*index2*x2+index2^2*x3
end
end
end
end
--Get y of patricular x
function self.getY(x)
if x > maxX or x < minX then
return
end
if maxX == minX and x == minX then
return minY, maxY
end
local index1, index2, buffer1, buffer2
local a = (x1 - x)
if a == 0 then
return
end
local b = xb
local c = xc
local discriminant = b^2 - 4*a*c
if discriminant < 0 then
return
else
local aByTwo = 2*a
local theSQRT = math.sqrt(discriminant)
if discriminant == 0 then
local index1 = -b/aByTwo
return (1-index1)^2*y1+2*(1-index1)*index1*y2+index1^2*y3
else
local index1, index2 = (-b - theSQRT)/aByTwo, (-b + theSQRT)/aByTwo
return (1-index1)^2*y1+2*(1-index1)*index1*y2+index1^2*y3, (1-index2)^2*y1+2*(1-index2)*index2*y2+index2^2*y3
end
end
end
--Scanline render
function self.scanRender()
local path = {}
local counter = 1
local fX, sX
local a = (y3 - 2*y2 + y1)
local b = 2*(y2 - y1)
for i=minY, maxY do
fX, sX = self.getX(i,a,b)
if fX then
path[counter] = fX
path[counter+1] = i
counter = counter + 2
if sX then
path[counter] = sX
path[counter+1] = i
counter = counter + 2
end
end
end
return path
end
--More efficient
--Self
return self
end
局部函数贝塞尔(x1,y1,x2,y2,x3,y3)
--私人的
本地inf=1/0
局部x1=x1
局部y1=y1
局部x2=x2
本地y2=y2
局部x3=x3
局部y3=y3
局部最大值=y1>y2和(y1>y3和y1或y3)或y2>y3和y2或y3
局部minY=y1