Software Design Model

Design Mode(English:Design PatternThis term was introduced from the architectural design field to computer science by Erich Gamma and others in the 1990 s. It is a solution to all kinds of problems that occur frequently in software design. The design pattern is not directly used to write code, but to describe how to solve the problem in different situations. Object-Oriented Design Patterns generally describe the relationships and interactions between categories or objects, but do not involve specific categories or objects used to complete applications. Algorithms cannot be regarded as a design pattern, because they are mainly used to solve computing problems rather than design problems. The design pattern is mainly to make the unstable dependent on relatively stable, specific dependent on relative abstraction, to avoid the trouble of tight coupling, in order to enhance the ability of the software design to face and adapt to changes.

Not all software models are design patterns, but design patterns are specific to software.DesignHierarchy issues. There are other non-design models, such as the architecture model.

With the increasing interest of the software development community in design patterns, relevant monographs have been published, and relevant seminars have been held on a regular basis. Ward cunnheim invented wikiwiki to exchange experience in design patterns.

 

Development History

Architect Christian Alexander compiled a collection in 1977/79Design Mode. However, the influence of this design pattern in the architectural design field is far from the extensive spread in the software development field.

In 1987, Kent Baker and wod kanning developed the architectural design field using the ideas of Christo Buddha Alexander.Design ModeThis idea is applied to the generation of graphic user interfaces in Smalltalk. One year later, Erich Gamma began to try to adapt this idea to software development in his PhD thesis at the University of Zurich. At the same time, James coplien used the same idea to develop C ++ from 1989 to 1991, and then published his book in 1991.Advanced C ++ Idioms. This year Erich Gamma got his doctorate and went to the United States, where he collaborated with Richard Helm, Ralph Johnson, and John vlissidesDesign Patterns-elements of reusable object-oriented softwareThis book contains 23Design Mode.

In the field of software development, these four authors are also known as Gang of Four (gof) anonymously, and collaboration in this book has led to a breakthrough in the software design model. Sometimes this anonymous gof is used to refer to the book mentioned above.

 

Statement format

The format of expressing a software design pattern varies with the author, such as the division and name. The format of common gof description modes is roughly divided into the following parts:

• Pattern name: each pattern has its own name. The pattern name allows us to discuss our design.
• Problem: in specific situations that occur repeatedly during the object-oriented system design process, it leads us to adopt a certain mode.
• Solution: the solution of the above problem provides the components of the design, the relationship between them, the division of duties and the way of collaboration.
• Alias: A mode can have more than one name. These names should be noted in this section.
• Motivation: This model should take advantage of the circumstances in which it is the responsibility of the solution provided in this section, including the problem and context.
• Applicability: applicable situations and background of the mode.
• Structure: This section describes the common class diagram and interaction diagram.
• Participants: This section provides a list of classes and objects used in this model, and their roles under design.
• Cooperation: Describes the interaction between classes and objects in this mode.
• Impact: the impact of this mode on other parts of the software system, such as the expansion and portability of the system. The impact also includes negative effects. This part should describe the results, side effects, trade-off)
• Implementation: This part should describe the implementation mode, some schemes of the mode, possible technologies for implementing the mode, or methods for implementing the mode.
• Example: briefly describe how to use patterns in programming languages.
• Known applications: an industry-known example of implementation.
• Related mode: This part includes other related modes and differences from other similar modes.

 

Category

Design PatternsThe book originally divided the design pattern into the creation pattern, the structure pattern, and the behavior pattern. describe them through the concepts of authorization, aggregation, and diagnosis. to learn more about the background of object-oriented design, refer to interface mode and cohesion. to learn more about the background of object-oriented programming, refer to inheritance, interfaces, and polymorphism.

Mode name	Description	InDesign Patterns	InCode Daquan[1]
Creation Mode
Abstract Factory Model	Provides a unified creation interface for a product family. When you need a series of products of this product family, you can select the corresponding series from the abstract factory to create a specific factory class.	Yes	Yes
Factory method mode	Define an interface to create an object, but let the subclass decide which class to initialize. The factory method puts the initialization of a class into the subclass.	Yes	Yes
Generator Mode	Separates the construction of a complex object from its representation, so that different representations can be created during the same construction process.	Yes	No
Lazy initialization Mode	Deferred object creation, data computing, and other operations that require a large amount of resources, only executed during the first access.	No	No
Object pool Mode	The high cost of obtaining and releasing resources is avoided by recycling the exploitation objects.	No	No
Prototype	Use a prototype instance to specify the type of the object to be created, and copy the prototype to create a new object.	Yes	No
Singleton Mode	Make sure that a class has only one instance and provides global access to the instance.	Yes	Yes
Structural Mode
Adapter Mode	Converts an interface of a class to another interface that the client expects. The adapter mode can eliminate Class compatibility problems caused by interface mismatch.	Yes	Yes
Bridging Mode	Decouples an abstraction and implementation so that the two can change independently.	Yes	Yes
Combination Mode	Multiple objects are structured in a tree to represent the local and the whole, so that users can treat the combination of a single object and an object in the same way.	Yes	Yes
Modifier Mode	Dynamically add more functions to an object. The modifier mode is a method that extends functions except class inheritance.	Yes	Yes
Appearance Mode	Provides a consistent interface for a group of interfaces in the subsystem. The appearance mode defines a high-level interface, which makes the subsystem easier to use.	Yes	Yes
Meta Mode	Through sharing, we can effectively support a large number of small particle objects.	Yes	No
Proxy Mode	Provide a proxy for other objects to control access to this object.	Yes	No
Behavior mode
Responsibility Chain Model	To cancel the coupling between the request sender and receiver, multiple objects have the opportunity to process the request. Connect these objects into a chain and pass the request along the chain until an object processes it.	Yes	No
Command mode	Encapsulate a request as an object so that you can parameterize the customer with different requests, queue requests or record request logs, and support cancelable operations.	Yes	No
Interpreter Mode	Given a language, it defines a syntax expression and an interpreter that uses this representation to interpret sentences in the language.	Yes	No
Iterator Mode	Provides a method to access each element in an aggregate object sequentially without exposing the internal representation of the object.	Yes	Yes
Mediator	Define an object that encapsulates how a set of Objects interact. mediator promotes loose coupling by keeping objects from referring to each other explicitly, and it lets you vary their interaction independently.	Yes	No
Memorandum Mode	Without violating encapsulation, capture and externalize an object's internal state so that the object can be restored to this State later.	Yes	No
Observer Mode	Define a one-to-many relationship between objects. When an object changes state, all other related objects are notified and automatically refreshed.	Yes	Yes
Status Mode	Allow an object to alter its behavior when its internal state changes. The object will appear to change its class.	Yes	No
Rule Mode	Define an algorithm series, package them separately, and make them interactive. The policy mode allows the algorithm to be changed independently when used by users.	Yes	Yes
Specification	Recombinable business logic in a Boolean fashion	No	No
Template Method Mode	Define the skeleton of an algorithm in an operation, deferring some steps to subclasses. template method lets subclasses redefine certain steps of Algorithm without changing the algorithm's structure.	Yes	Yes
Visitor Mode	Represent an operation to be performed med on the elements of an object structure. Visitor lets you define a new operation without changing the classes of Elements on which it operates.	Yes	No
Single-serving visitor	Optimize the implementation of a visitor that is allocated, used only once, and then deleted	No	No
Hierarchical visitor	Provide a way to visit every node in a hierarchical data structure such as a tree.	No	No
Concurrency Mode
Active Object		No	No
Balking		No	No
Double checked locking		No	No
Guarded		No	No
Leaders/followers		No	No
Monitor object		No	No
Read Write lock		No	No
Scheduler		No	No
Thread Pool Mode		No	No
Thread-specific storage		No	No
Reactor		No	No