Solid Software Development
My Interpretation of the Solid Principles of Object Oriented Design
Solid Development Principles from Michael Kappel on Vimeo.
Principles of Object Oriented Design at TechNexus for CITAG the Chicago Information Technology Architects Group on August, 16th 2011
Single responsibility principle
the notion that an object should have only a single responsibility.
the notion that "software entities … should be open for extension, but closed for modification".
Liskov substitution principle
the notion that "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
the notion that "many client specific interfaces are better than one general purpose interface."
Dependency inversion principle
the notion that one should "Depend upon Abstractions. Do not depend upon concretions."
Dependency injection is one method of following this principle.