shared-class-variable-references.py

#!/usr/bin/env python3


class C:
    a = 1

    def __init__(self):
        self.a += 1

    def update(self):
        self.a += 1


print(C.a)
c = C()
print(c.a)
c.update()
print(c.a)

print('---')

print(C.a)
c = C()
print(c.a)
c.update()
print(c.a)


print('---' * 2)


class C:
    a = []

    def __init__(self):
        self.a.append(1)

    def update(self):
        self.a.append(1)


print(C.a)
c = C()
print(c.a)
c.update()
print(c.a)

print('---')

print(C.a)
c = C()
print(c.a)
c.update()
print(c.a)

print('---' * 2)


class C:
    a = []

    def __init__(self):
        self.a = []
        self.a.append(1)

    def update(self):
        self.a.append(1)


print(C.a)
c = C()
print(c.a)
c.update()
print(c.a)

print('---')

print(C.a)
c = C()
print(c.a)
c.update()
print(c.a)


'''
> python3 x.py
1
2
3
---
1
2
3
------
[]
[1]
[1, 1]
---
[1, 1]
[1, 1, 1]
[1, 1, 1, 1]
------
[]
[1]
[1, 1]
---
[]
[1]
[1, 1]
'''