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Trait (computer programming)

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In <a href="Computer_programming" title="Computer programming">computer programming</a>, a trait is a <a href="Programming_language" title="Programming language">language</a> concept that represents a set of <a href="Method_(computer_programming)" title="Method (computer programming)">methods</a> that can be used to extend the functionality of a <a href="Class_(computer_science)" class="mw-redirect" title="Class (computer science)">class</a>.<a href="#cite_note-schaerli-ecoop-2003-1">[1]</a><a href="#cite_note-2">[2]</a>

<div class="mw-heading mw-heading2"><h2 id="Rationale">Rationale</h2></div>

In object-oriented programming, behavior is sometimes shared between classes which are not related to each other. For example, many unrelated classes may have methods to <a href="Serialization" title="Serialization">serialize</a> objects to <a href="JSON" title="JSON">JSON</a>. Historically, there have been several approaches to solve this without duplicating the code in every class needing the behavior. Other approaches include <a href="Multiple_inheritance" title="Multiple inheritance">multiple inheritance</a> and <a href="Mixin" title="Mixin">mixins</a>, but these have drawbacks: the behavior of the code may unexpectedly change if the order in which the mixins are applied is altered, or if new methods are added to the parent classes or mixins.

Traits solve these problems by allowing classes to use the trait and get the desired behavior. If a class uses more than one trait, the order in which the traits are used does not matter. The methods provided by the traits have direct access to the data of the class.

<div class="mw-heading mw-heading2"><h2 id="Characteristics">Characteristics</h2></div>

Traits combine aspects of <a href="Protocol_(object-oriented_programming)" class="mw-redirect" title="Protocol (object-oriented programming)">protocols (interfaces)</a> and <a href="Mixins" class="mw-redirect" title="Mixins">mixins</a>. Like an interface, a trait defines one or more <a href="Function_prototype" title="Function prototype">method signatures</a>, of which implementing classes must provide implementations. Like a mixin, a trait provides additional behavior for the implementing class.

In case of a <a href="Naming_collision" title="Naming collision">naming collision</a> between methods provided by different traits, the programmer must explicitly disambiguate which one of those methods will be used in the class; thus manually solving the <a href="Multiple_inheritance#The_diamond_problem" title="Multiple inheritance">diamond problem</a> of <a href="Multiple_inheritance" title="Multiple inheritance">multiple inheritance</a>. This is different from other composition methods in object-oriented programming, where conflicting names are automatically resolved by <a href="Scope_(computer_science)" title="Scope (computer science)">scoping rules</a>.

Operations which can be performed with traits include:<a href="#cite_note-3">[3]</a><a href="#cite_note-4">[4]</a>

<ul><li>symmetric sum: an operation that merges two disjoint traits to create a new trait</li>

<li>override (or asymmetric sum): an operation that forms a new trait by adding methods to an existing trait, possibly <a href="Method_overriding" title="Method overriding">overriding</a> some of its methods</li>

<li>alias: an operation that creates a new trait by adding a new name for an existing method</li>

<li>exclusion: an operation that forms a new trait by removing a method from an existing trait. (Combining this with the alias operation yields a shallow rename operation).</li></ul>

If a method is excluded from a trait, that method must be provided by the class that consumes the trait, or by a parent class of that class. This is because the methods provided by the trait might call the excluded method.

Trait composition is <a href="Commutative" class="mw-redirect" title="Commutative">commutative</a> (i.e. given traits A and B, A + B is equivalent to B + A) and <a href="Associative" class="mw-redirect" title="Associative">associative</a> (i.e. given traits A, B, and C, (A + B) + C is equivalent to A + (B + C)).<a href="#cite_note-schaerli-ecoop-2003-1">[1]</a>

<div class="mw-heading mw-heading2"><h2 id="Limitations">Limitations</h2></div>

While traits offer significant advantages over many alternatives, they do have their own limitations.

<div class="mw-heading mw-heading3"><h3 id="Required_methods">Required methods</h3></div>

If a trait requires the consuming class to provide certain methods, the trait cannot know if those methods are <a href="Semantic_equivalence" class="mw-redirect" title="Semantic equivalence">semantically equivalent</a> to the trait's needs. For some dynamic languages, such as Perl, the required method can only be identified by a method name, not a full <a href="Type_signature" title="Type signature">method signature</a>, making it harder to guarantee that the required method is appropriate.

<div class="mw-heading mw-heading3"><h3 id="Excluding_methods">Excluding methods</h3></div>

If a method is excluded from a trait, that method becomes a 'required' method for the trait because the trait's other methods might call it.

<div class="mw-heading mw-heading2"><h2 id="Supported_languages">Supported languages</h2></div>

Traits come originally from the programming language <a href="Self_(programming_language)" title="Self (programming language)">Self</a><a href="#cite_note-5">[5]</a> and are supported by the following programming languages:

<ul><li><a href="AmbientTalk" title="AmbientTalk">AmbientTalk</a>: Combines the properties of Self traits (object-based multiple inheritance) and <a href="Smalltalk" title="Smalltalk">Smalltalk</a>'s <a href="Squeak" title="Squeak">Squeak</a> traits (requiring explicit composition of traits by the programmer). It builds on the research on stateful and freezable traits to enable state within traits, which was not allowed in the first definitions.<a href="#cite_note-6">[6]</a></li>

<li><a href="C_Sharp_(programming_language)" title="C Sharp (programming language)">C#</a>: Since version 8.0, C# has support for default interface methods,<a href="#cite_note-7">[7]</a> which have some properties of traits.<a href="#cite_note-8">[8]</a></li>

<li><a href="C%2B%2B" title="C++">C++</a>: Used in <a href="Standard_Template_Library" title="Standard Template Library">Standard Template Library</a> and the <a href="C%2B%2B_Standard_Library" title="C++ Standard Library">C++ Standard Library</a> to support generic <a href="Container_(abstract_data_type)" title="Container (abstract data type)">container classes</a><a href="#cite_note-9">[9]</a><a href="#cite_note-10">[10]</a> and in the <a href="Boost_C%2B%2B_Libraries" class="mw-redirect" title="Boost C++ Libraries">Boost</a> TypeTraits library.<a href="#cite_note-11">[11]</a></li>

<li><a href="Curl_(programming_language)" title="Curl (programming language)">Curl</a>: Abstract classes as mixins permit method implementations and thus constitute traits by another name.</li>

<li><a href="Fortress_(programming_language)" title="Fortress (programming language)">Fortress</a><a href="#cite_note-12">[12]</a></li>

<li><a href="Groovy_(programming_language)" class="mw-redirect" title="Groovy (programming language)">Groovy</a>: Since version 2.3<a href="#cite_note-13">[13]</a></li>

<li><a href="Haskell_(programming_language)" class="mw-redirect" title="Haskell (programming language)">Haskell</a>: In Haskell, Traits are known as <a href="Type_class" title="Type class">Type classes</a>.</li>

<li><a href="Haxe" title="Haxe">Haxe</a>: Since version 2.4.0.<a href="#cite_note-14">[14]</a> Called Static Extension<a href="#cite_note-15">[15]</a> in the manual, it uses <code>using</code> keyword</li>

<li><a href="Java_(programming_language)" title="Java (programming language)">Java</a>: Since version 8, Java has support for default methods,<a href="#cite_note-16">[16]</a> which have some properties of traits.<a href="#cite_note-17">[17]</a><a href="#cite_note-18">[18]</a><a href="#cite_note-19">[19]</a><a href="#cite_note-20">[20]</a></li>

<li><a href="JavaScript" title="JavaScript">JavaScript</a>: Traits can be implemented via functions and delegations<a href="#cite_note-21">[21]</a> or through libraries that provide traits.<a href="#cite_note-22">[22]</a><a href="#cite_note-23">[23]</a><a href="#cite_note-24">[24]</a></li>

<li><a href="Julia_(programming_language)" title="Julia (programming language)">Julia</a>: Several packages implement traits, e.g.,<a href="#cite_note-25">[25]</a></li>

<li><a href="Kotlin_(programming_language)" title="Kotlin (programming language)">Kotlin</a>: Traits have been called interfaces<a href="#cite_note-26">[26]</a> since M12.<a href="#cite_note-27">[27]</a></li>

<li><a href="Lasso_(programming_language)" title="Lasso (programming language)">Lasso</a><a href="#cite_note-28">[28]</a></li>

<li><a href="Mojo_(programming_language)" title="Mojo (programming language)">Mojo</a>: Since version 0.6.0<a href="#cite_note-29">[29]</a></li>

<li><a href="OCaml" title="OCaml">OCaml</a>: Traits can be implemented using a variety of language features: module and module type inclusion, functors and functor types, class and class type inheritance, et cetera.</li>

<li><a href="Perl" title="Perl">Perl</a>: Called roles, they are implemented in Perl libraries such as <a href="Moose_(Perl)" title="Moose (Perl)">Moose</a>, Role::Tiny and Role::Basic. Roles are part of the sister language <a href="Raku_(programming_language)" title="Raku (programming language)">Raku</a>. <a href="#cite_note-30">[30]</a> With the acceptance of the Corinna OOP Proposal<a href="#cite_note-31">[31]</a> Perl will have roles native to the language as part of a modern OOP system.</li>

<li><a href="PHP" title="PHP">PHP</a>: Since version 5.4,<a href="#cite_note-32">[32]</a><a href="#cite_note-php:rfc:horizontalreuse-33">[33]</a> PHP allows users to specify templates that provide the ability to "inherit" from more than one (trait-)class, as a pseudo <a href="Multiple_inheritance" title="Multiple inheritance">multiple inheritance</a>.</li>

<li><a href="Python_(programming_language)" title="Python (programming language)">Python</a>: Via a third-party library,<a href="#cite_note-34">[34]</a><a href="#cite_note-35">[35]</a> or via higher-order mixin classes<a href="#cite_note-36">[36]</a></li>

<li><a href="Racket_(programming_language)" title="Racket (programming language)">Racket</a>: Supports traits as a library and uses macros, structures, and first-class classes to implement them.<a href="#cite_note-37">[37]</a></li>

<li><a href="Ruby_(programming_language)" title="Ruby (programming language)">Ruby</a>: Module mixins can be used to implement traits.<a href="#cite_note-38">[38]</a></li>

<li><a href="Scala_(programming_language)" title="Scala (programming language)">Scala</a><a href="#cite_note-40">[40]</a><a href="#cite_note-41">[41]</a> trait is builtin supported with the key word <code>trait</code>.</li>

<li><a href="Smalltalk" title="Smalltalk">Smalltalk</a>: Traits are implemented in two dialects of Smalltalk, <a href="Squeak" title="Squeak">Squeak</a><a href="#cite_note-schaerli-ecoop-2003-1">[1]</a> and <a href="Pharo" title="Pharo">Pharo</a>.<a href="#cite_note-42">[42]</a></li>

<li><a href="Swift_(programming_language)" title="Swift (programming language)">Swift</a>: Traits can be implemented with protocol extensions.<a href="#cite_note-43">[43]</a></li></ul>

<div class="mw-heading mw-heading2"><h2 id="Examples">Examples</h2></div>

On C# 8.0, it is possible to define an implementation as a member of an interface.<div class="mw-highlight mw-highlight-lang-c# mw-content-ltr" dir="ltr"><pre>using System;

namespace CSharp8NewFeatures;

interface ILogger

{

// Traditional interface methods

void Log(string message);

void LogError(Exception exception);

// Default interface method

void LogWarning(string message)

{

Console.WriteLine(message);

}

}

class Logger : ILogger

{

public void Log(string message)

{

Console.WriteLine(message);

}

public void LogError(Exception exception)

{

Console.WriteLine(exception.ToString());

}

}

class Program

{

static void Main(string[] args)

{

ILogger logger = new Logger();

logger.LogWarning("Some warning message");

}

}

</pre></div>

This example uses a trait to enhance other classes:

<div class="mw-highlight mw-highlight-lang-php mw-content-ltr" dir="ltr"><pre>// The template

trait TSingleton

{

private static $_instance = null;

private function __construct() {} // Must have private default constructor and be aware not to open it in the class

public static function getInstance()

{

if (null === self::$_instance) {

self::$_instance = new self();

}

return self::$_instance;

}

class FrontController

{

use TSingleton;

}

// Can also be used in already extended classes

class WebSite extends SomeClass

{

use TSingleton;

}

</pre></div>

This allows simulating aspects of multiple inheritance:

<div class="mw-highlight mw-highlight-lang-php mw-content-ltr" dir="ltr"><pre>trait TBounding

{

public $x, $y, $width, $height;

}

trait TMoveable

{

public function moveTo($x, $y)

{

// …

}

trait TResizeable

{

public function resize($newWidth, $newHeight)

{

// …

}

class Rectangle

{

use TBounding, TMoveable, TResizeable;

public function fillColor($color)

{

// …

}

</pre></div>

A trait in Rust declares a set of methods that a type must implement.<a href="#cite_note-44">[44]</a> Rust compilers require traits to be explicated, which ensures the safety of <a href="Generic_programming" title="Generic programming">generics</a> in Rust.

<div class="mw-highlight mw-highlight-lang-rust mw-content-ltr" dir="ltr"><pre>// type T must have the "Ord" trait

// so that ">" and "<" operations can be done

fn max<T: Ord>(a: &[T]) -> Option<&T> {

let mut result = a.first()?;

for n in a {

if *n > *result {

result = &n;

}

Some(result)

}

</pre></div>

To simplify tedious and repeated implementation of traits like <code>Debug</code> and <code>Ord</code>, the <code>derive</code> macro can be used to request compilers to generate certain implementations automatically.<a href="#cite_note-45">[45]</a> Derivable traits include: <code>Clone</code>, <code>Copy</code>, <code>Debug</code>, <code>Default</code>, <code>PartialEq</code>, <code>Eq</code>, <code>PartialOrd</code>, <code>Ord</code> and <code>Hash</code>.

<ul><li><a href="Extension_method" title="Extension method">Extension method</a></li>

<li><a href="Interface_(object-oriented_programming)" title="Interface (object-oriented programming)">Interface (object-oriented programming)</a></li>

<li><a href="Parametric_polymorphism" title="Parametric polymorphism">Parametric polymorphism</a></li>

<div class="mw-heading mw-heading2"><h2 id="References">References</h2></div>

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</style><cite id="CITEREFSchärliDucasseNierstraszBlack2003" class="citation book cs1">Schärli, Nathanael; Ducasse, Stéphane; <a href="Oscar_Nierstrasz" title="Oscar Nierstrasz">Nierstrasz, Oscar</a>; Black, Andrew P. (2003). <a rel="nofollow" class="external text" href="http://scg.unibe.ch/archive/papers/Scha03aTraits.pdf">"Traits: Composable Units of Behaviour"</a> (PDF). Proceedings of the European Conference on Object-Oriented Programming (ECOOP). Lecture Notes in Computer Science. Vol. 2743. Springer. pp. 248–274. <a href="CiteSeerX_(identifier)" class="mw-redirect" title="CiteSeerX (identifier)">CiteSeerX</a> <a rel="nofollow" class="external text" href="https://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.1011.8">10.1.1.1011.8</a>. <a href="Doi_(identifier)" class="mw-redirect" title="Doi (identifier)">doi</a>:<a rel="nofollow" class="external text" href="https://doi.org/10.1007%2F978-3-540-45070-2_12">10.1007/978-3-540-45070-2_12</a>. <a href="ISBN_(identifier)" class="mw-redirect" title="ISBN (identifier)">ISBN</a> <bdi>978-3-540-45070-2</bdi>.</cite>

</li>

<li id="cite_note-2"><a href="#cite_ref-2">^</a> <cite id="CITEREFDucasseNierstraszSchärliWuyts2006" class="citation journal cs1">Ducasse, Stéphane; Nierstrasz, Oscar; Schärli, Nathanael; Wuyts, Roel; Black, Andrew P. (March 2006). "Traits: A mechanism for fine-grained reuse". ACM Transactions on Programming Languages and Systems. 28 (2): 331–388. <a href="CiteSeerX_(identifier)" class="mw-redirect" title="CiteSeerX (identifier)">CiteSeerX</a> <a rel="nofollow" class="external text" href="https://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.64.2480">10.1.1.64.2480</a>. <a href="Doi_(identifier)" class="mw-redirect" title="Doi (identifier)">doi</a>:<a rel="nofollow" class="external text" href="https://doi.org/10.1145%2F1119479.1119483">10.1145/1119479.1119483</a>. <a href="S2CID_(identifier)" class="mw-redirect" title="S2CID (identifier)">S2CID</a> <a rel="nofollow" class="external text" href="https://api.semanticscholar.org/CorpusID:16434119">16434119</a>.</cite>

</li>

<li id="cite_note-3"><a href="#cite_ref-3">^</a> <cite id="CITEREFFisherReppy2003" class="citation report cs1"><a href="Kathleen_Fisher" title="Kathleen Fisher">Fisher, Kathleen</a>; Reppy, John (2003). <a rel="nofollow" class="external text" href="http://newtraell.cs.uchicago.edu/files/tr_authentic/TR-2003-13.pdf">Statically typed traits</a> (PDF) (Report). <a href="University_of_Chicago" title="University of Chicago">University of Chicago</a>. <a rel="nofollow" class="external text" href="https://web.archive.org/web/20040517161301/http://www.cs.uchicago.edu/files/tr_authentic/TR-2003-13.pdf">Archived</a> (PDF) from the original on May 17, 2004.</cite>

</li>

<li id="cite_note-4"><a href="#cite_ref-4">^</a> <cite id="CITEREFFisherReppy2004" class="citation conference cs1">Fisher, Kathleen; Reppy, John (2004). <a rel="nofollow" class="external text" href="http://people.cs.uchicago.edu/~jhr/papers/2004/fool-traits.pdf">A typed calculus of traits</a> (PDF). <a rel="nofollow" class="external text" href="http://www.cis.upenn.edu/~bcpierce/FOOL//FOOL11.html">11th Workshop on Foundations of Object-oriented Programming</a>. <a href="University_of_Chicago" title="University of Chicago">University of Chicago</a>.</cite>

</li>

<li id="cite_note-5"><a href="#cite_ref-5">^</a> <cite id="CITEREFCurryBaerLipkieLee1982" class="citation conference cs1">Curry, Gael; Baer, Larry; Lipkie, Daniel; Lee, Bruce (1982). Traits: An approach to multiple-inheritance subclassing. SIGOA Conference on Office Information Systems. Philadelphia, Pennsylvania, USA: ACM Press. pp. 1–9. <a href="Doi_(identifier)" class="mw-redirect" title="Doi (identifier)">doi</a>:<a rel="nofollow" class="external text" href="https://doi.org/10.1145%2F966873.806468">10.1145/966873.806468</a>.</cite>

</li>

<li id="cite_note-6"><a href="#cite_ref-6">^</a> <cite id="CITEREFVan_CutsemBergelDucasseDe_Meuter2009" class="citation conference cs1">Van Cutsem, Tom; Bergel, Alexandre; Ducasse, Stéphane; De Meuter, Wolfgang (2009). <a rel="nofollow" class="external text" href="http://soft.vub.ac.be/Publications/2009/vub-prog-tr-09-04.pdf">Adding State and Visibility Control to Traits Using Lexical Nesting</a> (PDF). European Conference on Object-Oriented Programming (ECOOP 2009). Lecture Notes in Computer Science. Vol. 5653. Springer-Verlag. pp. 220–243. <a href="CiteSeerX_(identifier)" class="mw-redirect" title="CiteSeerX (identifier)">CiteSeerX</a> <a rel="nofollow" class="external text" href="https://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.372.1265">10.1.1.372.1265</a>. <a href="Doi_(identifier)" class="mw-redirect" title="Doi (identifier)">doi</a>:<a rel="nofollow" class="external text" href="https://doi.org/10.1007%2F978-3-642-03013-0_11">10.1007/978-3-642-03013-0_11</a>. <a href="ISBN_(identifier)" class="mw-redirect" title="ISBN (identifier)">ISBN</a> <bdi>978-3-642-03012-3</bdi>.</cite>

</li>

<li id="cite_note-7"><a href="#cite_ref-7">^</a> <cite class="citation web cs1"><a rel="nofollow" class="external text" href="https://docs.microsoft.com/en-gb/dotnet/csharp/whats-new/csharp-8#default-interface-methods">"Default interface methods"</a>. What's new in C# 8.0. Microsoft. Retrieved November 29, 2019.</cite>

</li>

<li id="cite_note-8"><a href="#cite_ref-8">^</a> <cite class="citation web cs1"><a rel="nofollow" class="external text" href="https://www.talkingdotnet.com/default-implementations-in-interfaces-in-c-sharp-8/">"Interfaces in C# 8.0 gets a makeover"</a>. Default Implementation in Interfaces in C# 8.0. Talking Dotnet. 9 September 2019. Retrieved November 29, 2019.</cite>

</li>

<li id="cite_note-9"><a href="#cite_ref-9">^</a> <cite class="citation web cs1"><a rel="nofollow" class="external text" href="http://www.sgi.com/tech/stl/iterator_traits.html">"iterator_traits<Iterator>"</a>. Standard Template Library. SGI.</cite>

</li>

<li id="cite_note-10"><a href="#cite_ref-10">^</a> <cite id="CITEREFMyers1995" class="citation magazine cs1">Myers, Nathan C. (June 1995). <a rel="nofollow" class="external text" href="http://www.cantrip.org/traits.html">"Traits: a new and useful template technique"</a>. C++ Report. Retrieved January 23, 2016.</cite>

</li>

<li id="cite_note-11"><a href="#cite_ref-11">^</a> <cite id="CITEREFAbrahams" class="citation web cs1">Abrahams, David. <a rel="nofollow" class="external text" href="http://www.boost.org/more/generic_programming.html#traits">"Generic Programming Techniques: Traits"</a>. Boost C++ Libraries. Retrieved January 23, 2016.</cite>

</li>

<li id="cite_note-12"><a href="#cite_ref-12">^</a> <cite id="CITEREFSteeleMaessen2006" class="citation web cs1">Steele, Guy; Maessen, Jan-Willem (June 11, 2006). <a rel="nofollow" class="external text" href="http://stephane.ducasse.free.fr/Teaching/CoursAnnecy/0506-Master/ForPresentations/Fortress-PLDITutorialSlides9Jun2006.pdf">"Fortress Programming Language Tutorial"</a> (PDF). Sun Microsystems. Retrieved January 23, 2016.</cite>

</li>

<li id="cite_note-13"><a href="#cite_ref-13">^</a> <cite class="citation web cs1"><a rel="nofollow" class="external text" href="http://www.groovy-lang.org/objectorientation.html#_traits">"Object Orientation: Traits"</a>. The Groovy Programming Language. Retrieved January 23, 2016.</cite>

</li>

<li id="cite_note-14"><a href="#cite_ref-14">^</a> <cite class="citation news cs1"><a rel="nofollow" class="external text" href="https://haxe.org/download/version/2.4.0/">"Haxe 2.4.0 - Haxe - The Cross-platform Toolkit"</a>. Haxe - The Cross-platform Toolkit. Retrieved 2017-09-12.</cite>

</li>

<li id="cite_note-15"><a href="#cite_ref-15">^</a> <cite class="citation news cs1"><a rel="nofollow" class="external text" href="https://haxe.org/manual/lf-static-extension.html">"Manual - Haxe - The Cross-platform Toolkit"</a>. Haxe - The Cross-platform Toolkit. Retrieved 2017-09-12.</cite>

</li>

<li id="cite_note-16"><a href="#cite_ref-16">^</a> <cite class="citation web cs1"><a rel="nofollow" class="external text" href="https://docs.oracle.com/javase/tutorial/java/IandI/defaultmethods.html">"Default Methods"</a>. The Java Tutorials. Oracle. Retrieved January 23, 2016.</cite>

</li>

<li id="cite_note-17"><a href="#cite_ref-17">^</a> <cite id="CITEREFLiquoriSpiwack2008" class="citation journal cs1">Liquori, Luigi; Spiwack, Arnaud (2008). <a rel="nofollow" class="external text" href="https://hal.inria.fr/inria-00432538/">"FeatherTrait: A Modest Extension of Featherweight Java"</a>. ACM Transactions on Programming Languages and Systems. 30 (2): 11:1. <a href="Doi_(identifier)" class="mw-redirect" title="Doi (identifier)">doi</a>:<a rel="nofollow" class="external text" href="https://doi.org/10.1145%2F1330017.1330022">10.1145/1330017.1330022</a>. <a href="S2CID_(identifier)" class="mw-redirect" title="S2CID (identifier)">S2CID</a> <a rel="nofollow" class="external text" href="https://api.semanticscholar.org/CorpusID:17231803">17231803</a>.</cite>

</li>

<li id="cite_note-18"><a href="#cite_ref-18">^</a> <cite id="CITEREFLiquoriSpiwack2008" class="citation journal cs1">Liquori, Luigi; Spiwack, Arnaud (2008). <a rel="nofollow" class="external text" href="https://hal.inria.fr/inria-00432540/">"Extending FeatherTrait Java with Interfaces"</a>. Theoretical Computer Science. 398 (1–3): 243–260. <a href="Doi_(identifier)" class="mw-redirect" title="Doi (identifier)">doi</a>:<a rel="nofollow" class="external text" href="https://doi.org/10.1016%2Fj.tcs.2008.01.051">10.1016/j.tcs.2008.01.051</a>. <a href="S2CID_(identifier)" class="mw-redirect" title="S2CID (identifier)">S2CID</a> <a rel="nofollow" class="external text" href="https://api.semanticscholar.org/CorpusID:12923128">12923128</a>.</cite>

</li>

<li id="cite_note-19"><a href="#cite_ref-19">^</a> <cite id="CITEREFBonoMensaNaddeo2014" class="citation conference cs1">Bono, Viviana; Mensa, Enrico; Naddeo, Marco (September 2014). <a rel="nofollow" class="external text" href="https://hal.inria.fr/hal-01026531/en">Trait-oriented Programming in Java 8</a>. <a rel="nofollow" class="external text" href="http://pppj2014.pk.edu.pl/">International Conference on Principles and Practices of Programming on the Java Platform: virtual machines, languages, and tools (PPPJ ’14)</a>. pp. 181–6. <a href="CiteSeerX_(identifier)" class="mw-redirect" title="CiteSeerX (identifier)">CiteSeerX</a> <a rel="nofollow" class="external text" href="https://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.902.161">10.1.1.902.161</a>. <a href="Doi_(identifier)" class="mw-redirect" title="Doi (identifier)">doi</a>:<a rel="nofollow" class="external text" href="https://doi.org/10.1145%2F2647508.2647520">10.1145/2647508.2647520</a>.</cite>

</li>

<li id="cite_note-20"><a href="#cite_ref-20">^</a> <cite id="CITEREFForslund2016" class="citation web cs1">Forslund, Emil (February 3, 2016). <a rel="nofollow" class="external text" href="https://web.archive.org/web/20160804005218/http://ageofjava.com/2016/02/definition-of-trait-pattern-in-java.html">"Definition of the Trait Pattern in Java"</a>. Age of Java. Archived from <a rel="nofollow" class="external text" href="http://ageofjava.com/2016/02/definition-of-trait-pattern-in-java.html">the original</a> on August 4, 2016. Retrieved February 3, 2016.</cite>

</li>

<li id="cite_note-21"><a href="#cite_ref-21">^</a> <cite id="CITEREFSeliger2014" class="citation web cs1">Seliger, Peter (April 11, 2014). <a rel="nofollow" class="external text" href="http://peterseliger.blogspot.com/2014/04/the-many-talents-of-javascript.html">"The Many Talents of JavaScript"</a>. Retrieved January 23, 2015.</cite>

</li>

<li id="cite_note-22"><a href="#cite_ref-22">^</a> <cite class="citation web cs1"><a rel="nofollow" class="external text" href="https://traitsjs.github.io/traits.js-website/">"Traits.js: Traits for JavaScript"</a>. Retrieved January 23, 2016.</cite>

</li>

<li id="cite_note-23"><a href="#cite_ref-23">^</a> <cite id="CITEREFVan_CutsemMiller2012" class="citation journal cs1">Van Cutsem, Tom; Miller, Mark S. (2012). <a rel="nofollow" class="external text" href="http://soft.vub.ac.be/Publications/2012/vub-soft-tr-12-19.pdf">"Robust Trait Composition for Javascript"</a> (PDF). Science of Computer Programming. Retrieved January 23, 2016.</cite>

</li>

<li id="cite_note-24"><a href="#cite_ref-24">^</a> <cite class="citation web cs1"><a rel="nofollow" class="external text" href="https://cocktailjs.github.io/">"CocktailJS"</a>. Retrieved January 23, 2016.</cite>

</li>

<li id="cite_note-25"><a href="#cite_ref-25">^</a> <cite id="CITEREFMauro_Werder" class="citation web cs1">Mauro Werder. <a rel="nofollow" class="external text" href="https://github.com/mauro3/SimpleTraits.jl">"SimpleTraits.jl"</a>. <a href="GitHub" title="GitHub">GitHub</a>. Retrieved March 23, 2017.</cite>

</li>

<li id="cite_note-26"><a href="#cite_ref-26">^</a> <cite class="citation web cs1"><a rel="nofollow" class="external text" href="http://kotlinlang.org/docs/reference/interfaces.html">"Interfaces"</a>. Kotlin Reference. JetBrains. Retrieved January 23, 2016.</cite>

</li>

<li id="cite_note-27"><a href="#cite_ref-27">^</a> <cite id="CITEREFBreslav2015" class="citation web cs1">Breslav, Andrey (May 29, 2015). <a rel="nofollow" class="external text" href="http://blog.jetbrains.com/kotlin/2015/05/kotlin-m12-is-out/">"Kotlin M12 is out!"</a>. Kotlin Blog. JetBrains. Retrieved January 23, 2016.</cite>

</li>

<li id="cite_note-28"><a href="#cite_ref-28">^</a> <cite class="citation web cs1"><a rel="nofollow" class="external text" href="http://lassoguide.com/language/traits.html">"Traits"</a>. Lasso Language Guide. LassoSoft. January 6, 2014. Retrieved January 23, 2016.</cite>

</li>

<li id="cite_note-29"><a href="#cite_ref-29">^</a> <cite class="citation web cs1"><a rel="nofollow" class="external text" href="https://docs.modular.com/mojo/changelog.html#v0.6.0-2023-12-04">"Modular Docs - Mojo🔥 changelog"</a>. docs.modular.com. Retrieved 2023-12-13.</cite>

</li>

<li id="cite_note-30"><a href="#cite_ref-30">^</a> <cite id="CITEREFchromatic2009" class="citation web cs1">chromatic (April 30, 2009). <a rel="nofollow" class="external text" href="http://www.modernperlbooks.com/mt/2009/04/the-why-of-perl-roles.html">"The Why of Perl Roles"</a>. Retrieved January 23, 2016.</cite>

</li>

<li id="cite_note-31"><a href="#cite_ref-31">^</a> <cite id="CITEREFCurtis_"Ovid"_Poe" class="citation web cs1">Curtis "Ovid" Poe. <a rel="nofollow" class="external text" href="https://github.com/Ovid/Cor/blob/master/rfc/mvp.md">"Corinna OOP Proposal"</a>. Corinna RFC. Retrieved September 30, 2022.</cite>

</li>

<li id="cite_note-32"><a href="#cite_ref-32">^</a> <cite class="citation web cs1"><a rel="nofollow" class="external text" href="http://www.php.net/manual/en/language.oop5.traits.php">"Traits"</a>. PHP Documentation. The PHP Group. Retrieved January 23, 2016.</cite>

</li>

<li id="cite_note-php:rfc:horizontalreuse-33"><a href="#cite_ref-php:rfc:horizontalreuse_33-0">^</a> <cite id="CITEREFMarr2011" class="citation web cs1">Marr, Stefan (January 9, 2011). <a rel="nofollow" class="external text" href="https://wiki.php.net/rfc/horizontalreuse">"Request for Comments: Horizontal Reuse for PHP"</a>. PHP.net wiki. The PHP Group. Retrieved January 31, 2011.</cite>

</li>

<li id="cite_note-34"><a href="#cite_ref-34">^</a> <cite id="CITEREFPerä" class="citation web cs1">Perä, Teppo. <a rel="nofollow" class="external text" href="http://py3traits.readthedocs.org/">"py3traits Documentation"</a>. Retrieved January 23, 2016.</cite>

</li>

<li id="cite_note-35"><a href="#cite_ref-35">^</a> <cite id="CITEREFPerä2015" class="citation web cs1">Perä, Teppo (2015-03-25). <a rel="nofollow" class="external text" href="https://github.com/Debith/py2traits">"py2traits"</a>. <a href="GitHub" title="GitHub">GitHub</a>. Retrieved January 23, 2016.</cite>

</li>

<li id="cite_note-36"><a href="#cite_ref-36">^</a> <cite class="citation web cs1"><a rel="nofollow" class="external text" href="https://web.archive.org/web/20161009062141/http://stupid-python-tricks.blogspot.com/2015/04/computed-properties-and-higher-order.html">"Higher Order Mixin Classes"</a>. Archived from <a rel="nofollow" class="external text" href="http://stupid-python-tricks.blogspot.com/2015/04/computed-properties-and-higher-order.html">the original</a> on 2016-10-09.</cite>

</li>

<li id="cite_note-37"><a href="#cite_ref-37">^</a> <cite class="citation web cs1"><a rel="nofollow" class="external text" href="http://docs.racket-lang.org/reference/trait.html">"Traits"</a>. The Racket Reference. Retrieved January 23, 2016.</cite>

</li>

<li id="cite_note-38"><a href="#cite_ref-38">^</a> <cite id="CITEREFDavid_Naseby2004" class="citation web cs1">David Naseby (February 14, 2004). <a rel="nofollow" class="external text" href="http://ruby-naseby.blogspot.com/2008/11/traits-in-ruby.html">"Traits in Ruby"</a>. Ruby Naseby. Retrieved January 23, 2016.</cite>

</li>

<li id="cite_note-39"><a href="#cite_ref-39">^</a> <cite class="citation web cs1"><a rel="nofollow" class="external text" href="https://doc.rust-lang.org/book/ch10-02-traits.html">"Traits"</a>. The Rust Programming Language. Retrieved September 30, 2019.</cite>

</li>

<li id="cite_note-40"><a href="#cite_ref-40">^</a> <cite class="citation web cs1"><a rel="nofollow" class="external text" href="http://www.scala-lang.org/node/126">"Traits"</a>. A Tour of Scala. <a href="%C3%89cole_polytechnique_f%C3%A9d%C3%A9rale_de_Lausanne" class="mw-redirect" title="École polytechnique fédérale de Lausanne">École polytechnique fédérale de Lausanne</a>. Retrieved January 23, 2016.</cite>

</li>

<li id="cite_note-41"><a href="#cite_ref-41">^</a> <cite id="CITEREFNeward2008" class="citation web cs1">Neward, Ted (April 29, 2008). <a rel="nofollow" class="external text" href="http://www.ibm.com/developerworks/java/library/j-scala04298/">"The busy Java developer's guide to Scala: Of traits and behaviors"</a>. IBM developerWorks. IBM. Retrieved January 23, 2016.</cite>

</li>

<li id="cite_note-42"><a href="#cite_ref-42">^</a> <cite class="citation web cs1"><a rel="nofollow" class="external text" href="http://pharo.gemtalksystems.com/book/LanguageAndLibraries/Traits/">"Traits in 10 minutes"</a>. Pharo: The CollaborActive Book. Retrieved January 23, 2016.</cite>

</li>

<li id="cite_note-43"><a href="#cite_ref-43">^</a> <cite id="CITEREFHollemans2015" class="citation web cs1">Hollemans, Matthijs (July 22, 2015). <a rel="nofollow" class="external text" href="https://machinethink.net/blog/mixins-and-traits-in-swift-2.0/">"Mixins and Traits in Swift 2.0"</a>. Retrieved January 23, 2016.</cite>

</li>

<li id="cite_note-44"><a href="#cite_ref-44">^</a> <cite class="citation web cs1"><a rel="nofollow" class="external text" href="https://web.archive.org/web/20230529022632/http://gradebot.org/doc/ipur/trait.html">"Traits - Introduction to Programming Using Rust"</a>. Archived from <a rel="nofollow" class="external text" href="http://gradebot.org/doc/ipur/trait.html">the original</a> on 2023-05-29.</cite>

</li>

<li id="cite_note-45"><a href="#cite_ref-45">^</a> <cite class="citation web cs1"><a rel="nofollow" class="external text" href="https://doc.rust-lang.org/book/first-edition/traits.html">"Traits - the Rust Programming Language"</a>.</cite>

</li>

</ol></div>

<div class="mw-heading mw-heading2"><h2 id="External_links">External links</h2></div>

<ul><li><cite class="citation web cs1"><a rel="nofollow" class="external text" href="http://scg.unibe.ch/research/traits">"Traits: Composable Units of Behavior"</a>. Software Composition Group. University of Bern.</cite></li></ul></div><div><div class="zim-footer">

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