class Number():
list = []
number = Number()
number.list.append(0)
print number.list # [0]
newNumber = Number()
newNumber.list.append(1)
print newNumber.list # [0,1]
I have created two instance, why the newNumber.list object has the 0? Why the number and the newNumber use the same list? Anybody can help me? and Why the 'i' is not change in the follow?
class Number:
i = 0
number = Number()
number.i = 1
print number.i # 1
newNumber = Number()
print newNumber.i # 0
That's because you created the list as a member of the class object, rather than the instance objects. If you want to create a seperate list for each instance, you need to do something like this (I changed list to list_ since it's bad practice to give variables the same name as builtins).
class Number():
def __init__(self):
self.list_ = []
When you access an attribute on an object, it first checks the instance dictionary and then the class object dictionary. That's why making it a member of the class object didn't give you any errors. But since it's only a single list, every object will access that same list.
number.list means? It could be a plain property which stores some list, but it could also be the list type (constructor), for example I could do number.list('abc').
list object? I see no reason to expect a.list to be in any way related to list
class Number: i = 0 number = Number() number.i = 1 print number.i # 1 newNumber = Number() print newNumber.i # 0 why the newNumber.i is not 1?
listas defined in your code belongs to theclassnot the instances. you need to writeself.list = []to have onelistper instance