LUA Point class example 2
--
-- refine Point class for LUA
--
function class()
local cls = {}
cls.__index = cls
return setmetatable(cls,
{ __call = function (c, ...)
instance = setmetatable({}, cls)
if cls.__init then
cls.__init(instance, ...)
end
return instance
end
}
)
end
Point = class()
Point.key_list = {"x","y","z"}
function Point.__index(t,key)
error("No such Point member or init:"..key ,2)
end
function Point.__newindex(t,key,value)
for i = 1,#Point.key_list do
if key == Point.key_list[i] then
-- t[key] = value
rawset(t,key,value)
return
end
end
error("No such Point member :"..key ,2)
end
function Point:__init(...)
args = { ... }
if #args == 3 then
self.x = args[1]
self.y = args[2]
self.z = args[3]
elseif #args == 2 then
self.x = args[1]
self.y = args[2]
else
error("2D or 3D only" ,2)
end
end
function Point:__tostring()
local out = ""..self.x..","..self.y
local zz = rawget(self,"z")
if zz ~= nil then
out=out..","..self.z
end
return out
end
--
-- Usage
--
p1 = Point(1,2)
p2 = Point(3,4)
p1.x = 8
x1,y1=p1.x,p1.y
print(string.format("x1,y1=%d,%d",x1,y1))
-- p2 = p1
print(string.format("x2,y2=%d,%d",p2.x,p2.y))
--
local points = {p1,p2}
print("points[1].x=" .. points[1].x)
print("points[2].y=" .. points[2].y)
print("p1="..tostring(p1))
--print("p1="..p1)
p3 = Point(4,5,6)
print("p3="..tostring(p3))
--[[ below is two error test
print("p1.z="..p1.z) -- : No such Point member or init:z
p1.xxx = 567 -- : No such Point member :xxx
-- ]]
--
--[[ output
--
x1,y1=8,2
x2,y2=3,4
points[1].x=8
points[2].y=4
p1=8,2
p3=4,5,6
: No such Point member or init:z
: No such Point member :xxx
-- ]]
-- refine Point class for LUA
--
function class()
local cls = {}
cls.__index = cls
return setmetatable(cls,
{ __call = function (c, ...)
instance = setmetatable({}, cls)
if cls.__init then
cls.__init(instance, ...)
end
return instance
end
}
)
end
Point = class()
Point.key_list = {"x","y","z"}
function Point.__index(t,key)
error("No such Point member or init:"..key ,2)
end
function Point.__newindex(t,key,value)
for i = 1,#Point.key_list do
if key == Point.key_list[i] then
-- t[key] = value
rawset(t,key,value)
return
end
end
error("No such Point member :"..key ,2)
end
function Point:__init(...)
args = { ... }
if #args == 3 then
self.x = args[1]
self.y = args[2]
self.z = args[3]
elseif #args == 2 then
self.x = args[1]
self.y = args[2]
else
error("2D or 3D only" ,2)
end
end
function Point:__tostring()
local out = ""..self.x..","..self.y
local zz = rawget(self,"z")
if zz ~= nil then
out=out..","..self.z
end
return out
end
--
-- Usage
--
p1 = Point(1,2)
p2 = Point(3,4)
p1.x = 8
x1,y1=p1.x,p1.y
print(string.format("x1,y1=%d,%d",x1,y1))
-- p2 = p1
print(string.format("x2,y2=%d,%d",p2.x,p2.y))
--
local points = {p1,p2}
print("points[1].x=" .. points[1].x)
print("points[2].y=" .. points[2].y)
print("p1="..tostring(p1))
--print("p1="..p1)
p3 = Point(4,5,6)
print("p3="..tostring(p3))
--[[ below is two error test
print("p1.z="..p1.z) -- : No such Point member or init:z
p1.xxx = 567 -- : No such Point member :xxx
-- ]]
--
--[[ output
--
x1,y1=8,2
x2,y2=3,4
points[1].x=8
points[2].y=4
p1=8,2
p3=4,5,6
: No such Point member or init:z
: No such Point member :xxx
-- ]]
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