From Wikipedia, the free encyclopedia
Jump to navigation Jump to search

In object-oriented computer programming, SOLID is a mnemonic acronym for five design principles intended to make software designs more understandable, flexible, and maintainable. The principles are a subset of many principles promoted by American software engineer and instructor Robert C. Martin.[1][2][3]


The theory of SOLID principles was introduced by Robert C. Martin in his 2000 paper Design Principles and Design Patterns.[2][4]

The SOLID acronym was introduced later in 2004 or thereabouts by Michael Feathers.[5]


Although they apply to any object-oriented design, the SOLID principles can also form a core philosophy for methodologies such as agile development or adaptive software development.[3]

Single-responsibility principle[6]
A class should only have a single responsibility, that is, only changes to one part of the software's specification should be able to affect the specification of the class.
Open–closed principle[7]
"Software entities ... should be open for extension, but closed for modification."
Liskov substitution principle[8]
"Objects in a program should be replaceable with instances of their subtypes without altering the correctness of that program." See also design by contract.
Interface segregation principle[9]
"Many client-specific interfaces are better than one general-purpose interface."[4]
Dependency inversion principle[10]
One should "depend upon abstractions, [not] concretions."[4]

See also[edit]


  1. ^ Robert C. Martin. "Principles Of OOD". Retrieved 2014-07-17.. (Note the reference to "the first five principles", although the acronym is not used in this article.) Dates back to at least 2003.
  2. ^ a b Robert C. Martin. "Getting a SOLID start". Retrieved 2013-08-19.
  3. ^ a b Sandi Metz (May 2009). "SOLID Object-Oriented Design". Retrieved 2019-08-13. Talk given at the 2009 Gotham Ruby Conference.
  4. ^ a b c Martin, Robert C. (2000). "Design Principles and Design Patterns" (PDF). Archived from the original (PDF) on 2015-09-06.
  5. ^ Martin, Robert (2018). Clean Architecture: A Craftsman's Guide to Software Structure and Design. p. 58. ISBN 9780134494166.
  6. ^ "Single Responsibility Principle" (PDF). Archived from the original (PDF) on 2 February 2015.
  7. ^ "Open/Closed Principle" (PDF). Archived from the original (PDF) on 5 September 2015.
  8. ^ "Liskov Substitution Principle" (PDF). Archived from the original (PDF) on 5 September 2015.
  9. ^ "Interface Segregation Principle" (PDF). 1996. Archived from the original (PDF) on 5 September 2015.
  10. ^ "Dependency Inversion Principle" (PDF). Archived from the original (PDF) on 5 September 2015.


External links[edit]