pattern-memento

Capture and restore object state snapshots for undo history in TypeScript.

Updated Mar 26, 2026

Search Tags:#typescript #memento #undo #state-history #behavioral-pattern #caretaker #originator

Ready to run

npx skills add https://github.com/johnnystefan/test-saas-business --skill pattern-memento

💬 Prompt for ChatGPT / Claude Chat▼

Please help me install this Agent Skill.
Skill: pattern-memento
Source: https://github.com/johnnystefan/test-saas-business/tree/main/skills/design-patterns/behaviorals/pattern-memento
Command: npx skills add https://github.com/johnnystefan/test-saas-business --skill pattern-memento

SYSTEM DOCUMENTATION & REQUIREMENTS

What problem does it solve?

This skill explains how to capture and restore an object's private state so undo/redo, snapshots, and rollback features work without violating encapsulation.

Core Features & Use Cases

Originator and Memento roles: Define the Originator that creates mementos and the immutable Memento value object that stores its state.
Caretaker history: Keep clean history management outside the Originator so snapshots can be replayed or reverted safely.
Use Case: Apply the pattern when building draft/publish workflows, audit trails, or any feature that must restore complex domain objects to a prior state.

Quick Start

Use pattern-memento to snapshot the entity state before applying a risky update.

Frequently Asked Questions about pattern-memento

High-intent search queries and answers about installing and using this skill.

FAQPage Schema

How do I implement undo and redo functionality in TypeScript without exposing private object state?▼

The Memento pattern captures and restores object state snapshots to support undo history without breaking encapsulation. It separates state management into Originator, Memento, and Caretaker roles, ensuring immutable snapshots and clear encapsulation boundaries for safe rollback.

What is the Memento behavioral pattern and when should I use it?▼

The Memento pattern is a behavioral design technique that captures an object's private state into an immutable snapshot for later restoration. Use it when building undo/redo features, draft/publish workflows, audit trails, or any system needing to restore complex domain objects to a prior state.

How do I set up state history management for complex domain objects in TypeScript?▼

Set up state history by defining an immutable Memento value object to store state and an Originator to create snapshots. Keep history management in a separate Caretaker role so snapshots can be replayed or reverted safely without violating the domain object's encapsulation.

Does the Memento pattern support safe rollback for risky updates in object-oriented systems?▼

Yes, the Memento pattern supports safe rollback by capturing entity state snapshots before applying risky updates. It maintains immutable states and clear encapsulation boundaries across the Originator and Caretaker roles, ensuring safe restoration during complex rollback operations.

What are the limitations of using the Memento pattern for state history?▼

A key limitation of the Memento pattern for state history is potential memory overhead from storing multiple immutable snapshots of complex domain objects. It requires careful Caretaker management to ensure history does not consume excessive resources during frequent state capture.