https://docs.python.org/3/tutorial/classes.html#class-and-instance-variables
Class variables Python are strange.
If they are mutable, they act like STATIC PROPERTY in PHP;
If they are immutable, when they reassigned, the act like DYNAMIC PROPERTY in PHP.
It seems to do with reference.
class X:
array: list = []
immutable_array: tuple = ()
static_v: str = 'ori'
def __init__(self, name: str):
self.name = name
def init_ext(self):
self.array = []
# or even use [self.name], just let it be another id
def work(self):
self.array.append(self.name)
self.immutable_array = (len(self.array),)
self.static_v = f"[{self.name}]"
if __name__ == '__main__':
x1 = X("A")
x2 = X("B")
for i in range(3):
print("x1 array: ", x1.array, 'tuple: ', x1.immutable_array, "v: ", x1.static_v),
print("x1[id] array: ", id(x1.array), 'tuple: ', id(x1.immutable_array), "v: ", id(x1.static_v))
print("x2 array: ", x2.array, 'tuple: ', x2.immutable_array, "v: ", x2.static_v)
print("x2[id] array: ", id(x2.array), 'tuple: ', id(x2.immutable_array), "v: ", id(x2.static_v))
x1.work()
x2.work()
print("finally")
print("x1 array: ", x1.array, 'tuple: ', x1.immutable_array, "v: ", x1.static_v),
print("x1[id] array: ", id(x1.array), 'tuple: ', id(x1.immutable_array), "v: ", id(x1.static_v))
print("x2 array: ", x2.array, 'tuple: ', x2.immutable_array, "v: ", x2.static_v)
print("x2[id] array: ", id(x2.array), 'tuple: ', id(x2.immutable_array), "v: ", id(x2.static_v))
Output:
x1 array: [] tuple: () v: ori
x1[id] array: 4477451776 tuple: 4475306048 v: 4477483952
x2 array: [] tuple: () v: ori
x2[id] array: 4477451776 tuple: 4475306048 v: 4477483952
x1 array: ['A', 'B'] tuple: (1,) v: [A]
x1[id] array: 4477451776 tuple: 4476906464 v: 4477621936
x2 array: ['A', 'B'] tuple: (2,) v: [B]
x2[id] array: 4477451776 tuple: 4476375872 v: 4477622000
x1 array: ['A', 'B', 'A', 'B'] tuple: (3,) v: [A]
x1[id] array: 4477451776 tuple: 4476751488 v: 4477622064
x2 array: ['A', 'B', 'A', 'B'] tuple: (4,) v: [B]
x2[id] array: 4477451776 tuple: 4476906464 v: 4477621936
finally
x1 array: ['A', 'B', 'A', 'B', 'A', 'B'] tuple: (5,) v: [A]
x1[id] array: 4477451776 tuple: 4476375872 v: 4477622128
x2 array: ['A', 'B', 'A', 'B', 'A', 'B'] tuple: (6,) v: [B]
x2[id] array: 4477451776 tuple: 4476751488 v: 4477622064
If you execute init_ext after initialization, the result changed.
x1 = X("A")
x2 = X("B")
x1.init_ext()
x2.init_ext()
# the same test codes as above
The output would be :
x1 array: [] tuple: () v: ori
x1[id] array: 4327900992 tuple: 4325756992 v: 4327930800
x2 array: [] tuple: () v: ori
x2[id] array: 4327899904 tuple: 4325756992 v: 4327930800
x1 array: ['A'] tuple: (1,) v: [A]
x1[id] array: 4327900992 tuple: 4327849648 v: 4328077168
x2 array: ['B'] tuple: (1,) v: [B]
x2[id] array: 4327899904 tuple: 4327372112 v: 4328077232
x1 array: ['A', 'A'] tuple: (2,) v: [A]
x1[id] array: 4327900992 tuple: 4326822720 v: 4328077296
x2 array: ['B', 'B'] tuple: (2,) v: [B]
x2[id] array: 4327899904 tuple: 4327849648 v: 4328077168
finally
x1 array: ['A', 'A', 'A'] tuple: (3,) v: [A]
x1[id] array: 4327900992 tuple: 4327372112 v: 4328077232
x2 array: ['B', 'B', 'B'] tuple: (3,) v: [B]
x2[id] array: 4327899904 tuple: 4326822720 v: 4328077296