Re-engineering -- object-oriented design principles -- s.o.l. I. D Design Principles

SRP-single Responsibility Principle

• Full name: single Responsibility Principle
• Definition: the definition of each context object (class, function, variable, etc.) should only contain a single responsibility
• Description: objects are highly encapsulated with a single responsibility. Changes to objects depend only on changes to a single responsibility. They are defined based on high cohesion in software design.
• Source: Robert C. Martin (Uncle Bob )《Agile Software Development, principles, patterns, and practices"2002
• Source: Tom Demarco 《Structured Analysis and systems SpecificationProposed cohesion 1979
• Declaration: to make our classes more robust! A class shoshould have only one reason to change!

OCP-open-closed Principle

• Full name: open-closed Principle
• Definition: context objects (classes, modules, functions, etc.) should be open to extensions and closed to modifications.
• Description: uses the object-oriented polymorphism (polymorphic) to flexibly handle changes and embrace changes.
• Implementation: 1: Abstraction and inheritance; 2: interface-Oriented Programming
• Source: Robert C. Martin (Uncle Bob )《Agile Software Development, principles, patterns, and practices"2002
• Declaration: Protecting changes and embracing changes

LSP-liskov replacement principle

• Full name: liskov substitusion Principle
• Definition: A parent object can be replaced by a quilt object.
• Source: US first PhD in Computer ScienceBarbara liskovProfessor and Professor Jeannette Wing at Carnegie Mellon University proposed in 1994
• Scenario: behavior subtype, type abstraction, and inheritance. Design class abstraction, inheritance and Polymorphism
• Implementation: inversion of parameters (passed in) and covariance of returned (outgoing)
• DESIGN: contract-based design mode (Code contract of. NET Framework 4 seems to be another thing ?)
  • Preconditions: the preconditions cannot be reinforced in the subclass.
  • Post condition: the post condition cannot be weakened in the subclass.
  • Invariant: the Child-type invariant must be stored in the Child-type.
• Meaning: how can we design object type inheritance and interfaces (parameters and return value types)
• The following is an example of a violation of the liskov replacement principle:

  Static void drawshape (shape s) {If (S is rectangle) drawrectange (S as rectangle); else if (S is square) drawsquare (S as square ); else {//...}}

ISP-interface separation principle

• Full name: interface segregation principle
• Definition: users should not be forced to rely on methods they do not need
• Description: separates large coarse-grained interfaces into small-grained interfaces with clear specifications.
• Meaning: loose coupling facilitates reconstruction Iteration
• Interface: interface-oriented programming to reduce dependencies
• Source: Robert C. Martin (Uncle Bob )《Agile Software Development, principles, patterns, and practices"2002

Dip-Dependency inversion principle

• Full name: Dependency inversion principle
• Definition: dependent on abstraction, not on specifics, because abstraction is relatively stable
• Application: decoupling in applications through dependency Injection
  • Advanced modules should not depend on low-level modules. Both of them should depend on abstraction.
  • Abstraction should not depend on implementation details. Implementation Details should depend on abstraction.
• Meaning: Reuse low-level modules, reuse implementation, and remove Dependencies
• Implementation: through interfaces or abstract classes
• Others: plugin, service locator, or dependency Injection
• Source: Robert C. Martin (Uncle Bob )《Agile Software Development, principles, patterns, and practices"2002

Re-engineering -- object-oriented design principles -- s.o.l. I. D Design Principles