article

Stateful traits and their formalization

Authors:

Alexandre Bergel,

Stéphane Ducasse,

Oscar Nierstrasz,

Roel WuytsAuthors Info & Claims

Computer Languages, Systems and Structures, Volume 34, Issue 2-3

Pages 83 - 108

https://doi.org/10.1016/j.cl.2007.05.003

Published: 01 July 2008 Publication History

Abstract

Traits offer a fine-grained mechanism to compose classes from reusable components while avoiding problems of fragility brought by multiple inheritance and mixins. Traits as originally proposed are stateless, that is, they contain only methods, but no instance variables. State can only be accessed within stateless traits by accessors, which become required methods of the trait. Although this approach works reasonably well in practice, it means that many traits, viewed as software components, are artificially incomplete, and classes that use such traits may contain significant amounts of boilerplate glue code. We present an approach to stateful traits that is faithful to the guiding principle of stateless traits: the client retains control of the composition. Stateful traits consist of a minimal extension to stateless traits in which instance variables are purely local to the scope of a trait, unless they are explicitly made accessible by the composing client of a trait. We demonstrate by means of a formal object calculus that adding state to traits preserves the flattening property: traits contained in a program can be compiled away. We discuss and compare two implementation strategies, and briefly present a case study in which stateful traits have been used to refactor the trait-based version of the Smalltalk collection hierarchy.

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Cited By

Bergel AGhzouli RBerger TChaudron MMousavi MSchobbens P(2021)FeatureVistaProceedings of the 25th ACM International Systems and Software Product Line Conference - Volume A10.1145/3461001.3471154(196-201)Online publication date: 6-Sep-2021
https://dl.acm.org/doi/10.1145/3461001.3471154
Racordon DBuchs DLämmel RTratt Lde Lara J(2020)Featherweight Swift: a Core calculus for Swift’s type systemProceedings of the 13th ACM SIGPLAN International Conference on Software Language Engineering10.1145/3426425.3426939(140-154)Online publication date: 16-Nov-2020
https://dl.acm.org/doi/10.1145/3426425.3426939
Van den Vonder SDe Koster JDe Meuter W(2019)Composable Actor BehaviourDistributed Applications and Interoperable Systems10.1007/978-3-030-22496-7_4(57-73)Online publication date: 17-Jun-2019
https://dl.acm.org/doi/10.1007/978-3-030-22496-7_4
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Index Terms

Stateful traits and their formalization
1. Software and its engineering
  1. Software notations and tools
    1. General programming languages
      1. Language features
      2. Language types

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Published In

cover image Computer Languages, Systems and Structures

Computer Languages, Systems and Structures Volume 34, Issue 2-3

July, 2008

106 pages

ISSN:1477-8424

Issue’s Table of Contents

Copyright © Elsevier Ltd © 2007.

Publisher

Elsevier Science Publishers B. V.

Netherlands

Publication History

Published: 01 July 2008

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Cited By

Bergel AGhzouli RBerger TChaudron MMousavi MSchobbens P(2021)FeatureVistaProceedings of the 25th ACM International Systems and Software Product Line Conference - Volume A10.1145/3461001.3471154(196-201)Online publication date: 6-Sep-2021
https://dl.acm.org/doi/10.1145/3461001.3471154
Racordon DBuchs DLämmel RTratt Lde Lara J(2020)Featherweight Swift: a Core calculus for Swift’s type systemProceedings of the 13th ACM SIGPLAN International Conference on Software Language Engineering10.1145/3426425.3426939(140-154)Online publication date: 16-Nov-2020
https://dl.acm.org/doi/10.1145/3426425.3426939
Van den Vonder SDe Koster JDe Meuter W(2019)Composable Actor BehaviourDistributed Applications and Interoperable Systems10.1007/978-3-030-22496-7_4(57-73)Online publication date: 17-Jun-2019
https://dl.acm.org/doi/10.1007/978-3-030-22496-7_4
Bettini LDamiani F(2017)XtraitjJournal of Systems and Software10.1016/j.jss.2016.07.035131:C(419-441)Online publication date: 1-Sep-2017
https://dl.acm.org/doi/10.1016/j.jss.2016.07.035
Arnaud JDucasse SDenker MTeruel C(2015)HandlesScience of Computer Programming10.1016/j.scico.2014.07.01198:P3(318-338)Online publication date: 1-Feb-2015
https://dl.acm.org/doi/10.1016/j.scico.2014.07.011
Bettini LDamiani FSchaefer I(2015)Implementing type-safe software product lines using parametric traitsScience of Computer Programming10.1016/j.scico.2013.07.01697:P3(282-308)Online publication date: 1-Jan-2015
https://dl.acm.org/doi/10.1016/j.scico.2013.07.016
Bono VMensa ENaddeo MKolodziej JChilders B(2014)Trait-oriented programming in Java 8Proceedings of the 2014 International Conference on Principles and Practices of Programming on the Java platform: Virtual machines, Languages, and Tools10.1145/2647508.2647520(181-186)Online publication date: 23-Sep-2014
https://dl.acm.org/doi/10.1145/2647508.2647520
Bettini LDamiani FKolodziej JChilders B(2014)Generic traits for the Java platformProceedings of the 2014 International Conference on Principles and Practices of Programming on the Java platform: Virtual machines, Languages, and Tools10.1145/2647508.2647518(5-16)Online publication date: 23-Sep-2014
https://dl.acm.org/doi/10.1145/2647508.2647518
Wernli ENierstrasz OTeruel CDucasse SPeternier ABinder WErnst EHirschfeld R(2014)Delegation proxiesProceedings of the 13th international conference on Modularity10.1145/2577080.2577081(1-12)Online publication date: 22-Apr-2014
https://dl.acm.org/doi/10.1145/2577080.2577081
Damiani FDovland JJohnsen ESchaefer I(2014)Verifying traits: an incremental proof system for fine-grained reuseFormal Aspects of Computing10.1007/s00165-013-0278-326:4(761-793)Online publication date: 1-Jul-2014
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