Hands-On Design Patterns and Best Practices with Julia

The memento pattern

The memento pattern is a state management technique that you can use to restore your work to a previous state when needed. A common example is the Undo function of a word processor application. After making 10 changes, we can always undo the prior operations and return to the original state before those 10 changes were made. Similarly, an application may remember the most recently opened files and provide a menu of choices so that the user can quickly reopen a previously opened file.

Implementing the memento pattern in Julia is quite simple. We can just store previous states in an array and when making a change, we can push the new state to the array. When we want to undo our actions, we restore the previous state by popping ...