备忘录模式(Memento)用于保存一个对象的某个状态，以便在适当的时候恢复对象。备忘录模式属于行为型模式，主要包括源发器，备忘录以及负责人。源发器：普通类，可以创建备忘录，也可以使用备忘录恢复状态。备忘录：储存原发器内部状态，处理原发器和负责人类，备忘录不直接和其他类交互。负责人：保存备忘录，但是不对备忘录操作或检查
存档、undo 、数据库的事务管理用到了备忘录模式。本文参考以下类图，用matlab语言实现备忘录模式。
Originator.m
classdef Originator < handle
properties
state
end
methods
function mem = createMemento(obj)
mem = Memento(obj.state);
end
function restoreMemento(obj, mem)
obj.state = mem.state;
end
end
end
Memento.m
classdef Memento < handle & matlab.mixin.Heterogeneous
properties
state
end
methods
function obj = Memento(state)
obj.state = state;
end
end
end
CareTaker.m
classdef CareTaker < handle
properties
memento = Memento.empty();
end
methods
function add(obj, mem)
obj.memento(end + 1) = mem;
end
function mem = get(obj, index)
mem = obj.memento(index);
end
end
end
test.m
originator = Originator();
careTaker = CareTaker();
originator.state = "State #1";
originator.state = "State #2";
careTaker.add(originator.createMemento());
originator.state = "State #3";
careTaker.add(originator.createMemento());
originator.state = "State #4"; disp("Current State: " + originator.state);
originator.restoreMemento(careTaker.get(1));
disp("First saved State: " + originator.state);
originator.restoreMemento(careTaker.get(2));
disp("Second saved State: " + originator.state);
参考资料：
https://www.runoob.com/design-pattern/memento-pattern.html
https://blog.csdn.net/qq_40369829/article/details/80370606