OOP: Interface (Definitions)

"A contract that specifies the members a class or struct can implement to receive generic services for that type." (Jesse Liberty, "Programming C#" 2nd Ed., 2002)

"In Java, an interface is similar to a class definition, except that no detailed implementation of methods is provided. A class that implements an interface must provide the code to implement the methods. You can think of an interface as defining a contract between the calling method and the class that implements the interface." (Marcus Green & Bill Brogden, "Java 2™ Programmer Exam Cram™ 2 (Exam CX-310-035)", 2003)

"A set of signatures of public operations." (Craig Larman, "Applying UML and Patterns", 2004)

"A defined set of properties, methods, and collections that form a logical grouping of behaviors and data. Classes are defined by the interfaces that they implement. An interface can be implemented by many different classes." (Jim Joseph et al, "Microsoft SQL Server 2008 Reporting Services Unleashed", 2009)

"The specification of the means by which services can be invoked and data can be manipulated across an encapsulation boundary (e.g., class)." (Bruce P Douglass, "Real-Time Agility", 2009)

"The externally visible definition of the operations permitted on an application component." (David Lyle & John G Schmidt, "Lean Integration", 2010)

"Defines a set of members that a class can provide." (Rod Stephens, "Start Here! Fundamentals of Microsoft .NET Programming", 2011)

"Defines public properties, methods, and events that a class must provide to satisfy the interface." (Rod Stephens, "Stephens' Visual Basic Programming 24-Hour Trainer", 2011)

"A defined set of properties, methods, and collections that form a logical grouping of behaviors and data." (Microsoft, "SQL Server 2012 Glossary", 2012)

"The services a piece of code promises to provide forever, in contrast to its implementation, which it should feel free to change whenever it likes." (Jon Orwant et al, "Programming Perl" 4th Ed., 2012)

"A keyword used to declare an interface." (Daniel Leuck et al, "Learning Java" 5th Ed., 2020)