Saving class instance state from inside class

Question

I have read over the answers on Saving an Object (Data persistence) but it isn't really what I was looking for. I don't want to save the class state in a file.

Here's what I'm trying to implement:

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 - (*)

How can I save the class state at a particular point?

score 1 · Answer 1 · answered Apr 21 '22 at 11:50

You could implement something like this

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

Saving class instance state from inside class

1 Answers1