Problem with OOP in lua
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- Subject: Problem with OOP in lua
- From: 许斌 <xbcqu0708@...>
- Date: 2006年4月13日 17:01:06 +0800
Hi!
I'm using Lua.5.1, I have been trying to emulate class in Lua. I have been reading the chapter 16 in the PIL.
it does well, but it has a flaw:
Account = {balance = 0}
function Account:deposit(v)
self.balance = self.balance + v
end
function Account:new(o)
o = o or {}
setmetatable(o, self)
self.__index = self
return o
end
a = Account:new()
b = Account:new()
a:deposit(2)
print("a=", a.balance)
print("b=", b.balance)
output:
a=2
b=0
but there is a problem. if the balance is not a number, it's a table, as follows:
Account = {balance = {0}}
function Account:deposit(v)
self.balance[1] = self.balance[1] + v
end
function Account:new(o)
o = o or {}
setmetatable(o, self)
self.__index = self
return o
end
a = Account:new()
b = Account:new()
a:deposit(2)
print("a=", a.balance)
print("b=", b.balance)
output:
a = {2}
b = {2}
The instance a is changed and the instance b is changed too. This may be a flaw, how to improve it!
Thanks you!
----
bean