software development Software development is the process of designing and Implementation, implementing a software solution to Computer user satisfaction, satisfy a User (computing), user. The process is more encompassing than Computer programming, programming, wri ...

, the yo-yo problem is an

anti-pattern An anti-pattern in software engineering, project management, and business processes is a common response to a recurring problem that is usually ineffective and risks being highly counterproductive. The term, coined in 1995 by computer programmer An ...

that occurs when a programmer has to read and understand a program whose inheritance graph is so long and complicated that the programmer has to keep flipping between many different class definitions in order to follow the control flow of the program. It is most often seen in the context of

object-oriented programming Object-oriented programming (OOP) is a programming paradigm based on the concept of '' objects''. Objects can contain data (called fields, attributes or properties) and have actions they can perform (called procedures or methods and impl ...

. The term comes from comparing the bouncing attention of the programmer to the up-down movement of a toy yo-yo. Taenzer, Ganti, and Podar described the problem by name, explaining: "Often we get the feeling of riding a yoyo when we try to understand one of these message trees." Most practices of object-oriented programming recommend keeping the inheritance graph as shallow as possible, in part to avoid this problem. The use of

composition Composition or Compositions may refer to: Arts and literature *Composition (dance), practice and teaching of choreography * Composition (language), in literature and rhetoric, producing a work in spoken tradition and written discourse, to include ...

instead of

inheritance Inheritance is the practice of receiving private property, titles, debts, entitlements, privileges, rights, and obligations upon the death of an individual. The rules of inheritance differ among societies and have changed over time. Offi ...

is also strongly preferred, although this still requires that a programmer keep multiple class definitions in mind at once. Deep hierarchies are a

code smell In computer programming, a code smell is any characteristic in the source code of a program that possibly indicates a deeper problem. Determining what is and is not a code smell is subjective, and varies by language, developer, and development met ...

and a symptom of sub-classification for

code reuse Code reuse is the practice of using existing source code to develop software instead of writing new code. ''Software reuse'' is a broader term that implies using any existing software asset to develop software instead of developing it again. An as ...

. More generally, the yo-yo problem can also refer to any situation where a person must keep flipping between different sources of information in order to understand a concept. There are several code refactor techniques to flatten these hierarchies without compromising the overall behavior. Object-oriented design techniques such as documenting layers of the inheritance hierarchy can reduce the effect of this problem, as they collect in one place the information that the programmer is required to understand.

References

{{Reflist Object-oriented programming Anti-patterns

See also

References