In computing

Computing

Computing is usually defined as the activity of using and improving computer hardware and software. It is the computer-specific part of information technology...

, the C3 superclass linearization is an algorithm

Algorithm

In mathematics and computer science, an algorithm is an effective method expressed as a finite list of well-defined instructions for calculating a function. Algorithms are used for calculation, data processing, and automated reasoning...

 used primarily to obtain a consistent linearization

Linearization

In mathematics and its applications, linearization refers to finding the linear approximation to a function at a given point. In the study of dynamical systems, linearization is a method for assessing the local stability of an equilibrium point of a system of nonlinear differential equations or...

 of a multiple inheritance

Multiple inheritance

Multiple inheritance is a feature of some object-oriented computer programming languages in which a class can inherit behaviors and features from more than one superclass....

 hierarchy in object-oriented programming

Object-oriented programming

Object-oriented programming is a programming paradigm using "objects" – data structures consisting of data fields and methods together with their interactions – to design applications and computer programs. Programming techniques may include features such as data abstraction,...

. This linearization is used to resolve the order in which methods should be inherited, and is often termed "MRO" for Method Resolution Order. The name C3 refers to the three important properties of the resulting linearization: a consistent extended precedence graph

Precedence graph

A precedence graph, also named conflict graph and serializability graph, is used in the context of concurrency control in databases.The precedence graph for a schedule S contains:* A node for each committed transaction in S...

, preservation of local precedence order

Order of operations

In mathematics and computer programming, the order of operations is a rule used to clarify unambiguously which procedures should be performed first in a given mathematical expression....

, and monotonicity. It was first published at the 1996 OOPSLA

OOPSLA

OOPSLA is an annual ACM research conference. OOPSLA mainly takes place in the United States, while the sister conference of OOPSLA, ECOOP, is typically held in Europe...

 conference, in a paper entitled "A Monotonic Superclass Linearization for Dylan". Subsequently, it has been chosen as the default algorithm for method resolution in Python

Python (programming language)

Python is a general-purpose, high-level programming language whose design philosophy emphasizes code readability. Python claims to "[combine] remarkable power with very clear syntax", and its standard library is large and comprehensive...

 2.3 (and newer), Perl 6

Perl 6

Perl 6 is a major revision to the Perl programming language. It is still in development, as a specification from which several interpreter and compiler implementations are being written. It is introducing elements of many modern and historical languages. Perl 6 is intended to have many...

, and Parrot

Parrot virtual machine

Parrot is a register-based process virtual machine designed to run dynamic languages efficiently. It uses just-in-time compilation for speed to reduce the interpretation overhead. It is currently possible to compile Parrot assembly language and PIR to Parrot bytecode and execute it...

. It is also available as an alternative, non-default MRO in the core of Perl 5

Perl

Perl is a high-level, general-purpose, interpreted, dynamic programming language. Perl was originally developed by Larry Wall in 1987 as a general-purpose Unix scripting language to make report processing easier. Since then, it has undergone many changes and revisions and become widely popular...

 starting with version 5.10.0. An extension implementation for earlier versions of Perl 5 named Class::C3 exists on CPAN

CPAN

CPAN, the Comprehensive Perl Archive Network, is an archive of nearly 100,000 modules of software written in Perl, as well as documentation for it. It has a presence on the World Wide Web at and is mirrored worldwide at more than 200 locations...

.