从类内部保存类实例状态

Question

我已经阅读了关于保存对象(数据持久性)的答案，但这并不是我真正想要的。我不想把类的状态保存在文件中。

这是我想要实现的:

class A():
def some_function(self):
# save class state here - (*)
if something:
#make changes to class attributes
if something_again():
# revert back to class state at - (*)

如何保存特定点的类状态?

Answer 1

你可以这样实现

class A():
def __init__(self):
self.prev_state = dict()
self.field_1 = 1
self.field_2 = 2
self.save_fields = (
"field_1",
"field_2"
)
self.save_state()
def save_state(self):
for f in self.save_fields:
self.prev_state[f] = getattr(self, f)
def restore_state(self):
for f in self.save_fields:
setattr(self, f, self.prev_state[f])

a = A()
a.field_1 += 1
print(a.field_1) # 2
a.restore_state()
print(a.field_1) # 1