当前位置:网站首页>The memorandum model of behavior model
The memorandum model of behavior model
2020-11-06 21:35:00 【Irving the procedural ape】
Catalog
- Definition and characteristics
- Structure and Implementation
- The structure of the pattern
- The realization of pattern
- Application scenarios
- Expand : Mixed with prototype patterns
Everyone makes mistakes sometimes , I hope there is a kind of “ Regret ” Make up for your own mistakes , Let yourself start over , But the reality is brutal . In computer applications , Customers also make mistakes often , Can you provide “ Regret ” Give it to them ? Of course you can , And it's necessary . This function consists of “ Memo mode ” To achieve .
In fact, many applications provide this function , Such as Word、 Notepad 、Photoshop、Eclipse Wait for the software to press when editing Ctrl+Z Key combination can undo the current operation , Restore the document to its previous state ; And in IE Back key in 、 Rollback operation in database transaction management 、 Save intermediate results when playing games 、 Database and operating system backup operation 、 The repentance function in chess games belongs to this kind of game .
Memo mode can record the internal state of an object , When the user regrets, the current operation can be undone , Restore data to its original state .
Definition and characteristics
Memorandum (Memento) Pattern The definition of : Without breaking encapsulation , Capture the internal state of an object , And save the state outside the object , So that the object can be restored to the original saved state when needed later , This mode is also called snapshot mode .
Memo mode is an object behavior pattern , Its main advantages are as follows :
- Provides a mechanism for restoring state : When the user needs to be able to more easily restore the data to a historical state .
- Realize the encapsulation of internal state : In addition to the founders who created it , No other object can access this state information .
- Simplified the originator : Initiators do not need to manage and save individual backups of their internal state , All status information is stored in the memo , And managed by the manager , This is in line with the principle of single responsibility .
Its main drawback is : High resource consumption , If the internal state information to be saved is too much or too frequent , It will occupy a large amount of memory resources .
Structure and Implementation
The core of the memo pattern is to design the memo class and the manager class for managing the memo , Now let's learn about its structure and implementation .
The structure of the pattern
The main roles of the memo model are as follows :
- Originator (Originator) role : Record the internal status information of the current time , Provides the ability to create and recover memo data , Implement other business functions , It has access to all the information in the memo .
- Memorandum (Memento) role : Responsible for storing the internal state of the initiator , Provide these internal states to the originator when needed .
- managers (Caretaker) role : Manage memos , Provides the ability to save and retrieve memos , But it cannot access and modify the contents of the memorandum .
The structure of the memo mode is shown in the figure :
The realization of pattern
The implementation code of memo mode is as follows :
class Program{ static void Main(string[] args) { Originator or = new Originator(); Caretaker cr = new Caretaker(); or.SetState("S0"); Console.WriteLine(" The initial state :" + or.GetState()); cr.SetMemento(or.CreateMemento()); // Save state or.SetState("S1"); Console.WriteLine(" New status :" + or.GetState()); or.RestoreMemento(cr.GetMemento()); // Restore the state Console.WriteLine(" Restore the state :" + or.GetState()); Console.Read(); }}// Memorandum public class Memento{ private String state; public Memento(String state) { this.state=s.........
版权声明
本文为[Irving the procedural ape]所创,转载请带上原文链接,感谢
边栏推荐
- The role of theme music in games
- NAND FLASH的接口控制设计
- Will blockchain be the antidote to the global epidemic accelerating the transformation of Internet enterprises?
- How to play sortable JS vuedraggable to realize nested drag function of forms
- Novice guidance and event management system in game development
- From overseas to China, rancher wants to do research on container cloud market
- An article will introduce you to CSS3 background knowledge
- What is the meaning of sector sealing of filecoin mining machine since the main network of filecoin was put online
- The legality of IPFs / filecoin: protecting personal privacy from disclosure
- Small program introduction to proficient (2): understand the four important files of small program development
猜你喜欢
[byte jumps, autumn recruitment Posts open] ohayoo! Don't leave after school, I want to ask you to play games!!!
ado.net和asp.net的关系
Zhou Jie: database system of East China Normal University
2020-09-03:裸写算法:回形矩阵遍历。
ES中删除索引的mapping字段时应该考虑的点
Small program introduction to proficient (2): understand the four important files of small program development
This project allows you to quickly learn about a programming language in a few minutes
What are the highlights of Huawei mate 40 series with HMS?
An article will take you to understand SVG gradient knowledge
ERD-ONLINE 免费在线数据库建模工具
随机推荐
Introduction to Huawei cloud micro certification examination
This project allows you to quickly learn about a programming language in a few minutes
意外的元素..所需元素..
ES6 learning notes (3): teach you to use js object-oriented thinking to realize the function of adding, deleting, modifying and checking tab column
Qt音视频开发46-视频传输UDP版
The native API of the future trend of the front end: web components
行为型模式之解释器模式
Detect certificate expiration script
An article takes you to understand CSS pagination examples
The isolation level of transaction and its problems
Event monitoring problem
Top 5 Chinese cloud manufacturers in 2018: Alibaba cloud, Tencent cloud, AWS, telecom, Unicom
git远程库回退指定版本
行为型模式之备忘录模式
JVM memory allocation - xms128m - xmx512m - XX: permsize = 128M - XX: maxpermsize = 512M
STM32F030F4P6兼容灵动微MM32F031F4P6
Bitcoin once exceeded 14000 US dollars and is about to face the test of the US election
What is the purchasing supplier system? Solution of purchasing supplier management platform
Some operations kept in mind by the front end foundation GitHub warehouse management
[learning] interface test case writing and testing concerns