Principle SOLID 5 software design principles that help to create a good software architecture with :
- Tolerate change
- Easy code to understand
- Easy to maintain
- Write components that can be used in many software systems
- S: Single Responsibility Principle
- O: Open-Closed Principle
- LisKov Substitution Principle
- Interface Segregation Principle
- Dependency Inversion Principle
A class should have only one reason to change
We determine responsability of one class according to the social structure of the users usage.
Example: go to file SingleResponsibilityPrinciple
A class should be open for extension, but closed for modification
This principle is about extending the behavior of a class without modifying it. So to add new functionality, it shouldn't require changing the existing code.
Tips: To do this, we write interfaces and abstract classes in order to dictate the higher-level policy that needs to be implemented, and then we implement that policy using concrete classes.
Example: go to file OpenClosedPrinciple
Derived classes must be substitutable for their base classes
This principle is about inheritance and polymorphism. It states that if a program is using a base class, then the reference to the base class can be replaced with a derived class without affecting the functionality of the program.
Example: go to file LiskovSubstitutionPrinciple
A client should never be forced to implement an interface that it doesn't use
This principle is about interfaces. It states it’s better to have smaller, focused interfaces rather than large, monolithic ones.
Example: go to filesInterfaceSegregationPrinciple
High-level modules should not depend on low-level modules. Both should depend on abstractions.
- High-level modules are
interfacesandabstract classesthat define the policy of the application. - Low-level modules are the concrete
classesthat implement the policy.
Example: go to files DependencyInversionPrinciple