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Traits: Composable Units of Behaviour

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ECOOP 2003 – Object-Oriented Programming (ECOOP 2003)

Part of the book series: Lecture Notes in Computer Science ((LNCS,volume 2743))

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Abstract

Despite the undisputed prominence of inheritance as the fundamental reuse mechanism in object-oriented programming languages, the main variants—single inheritance, multiple inheritance, and mixin inheritance—all suffer from conceptual and practical problems. In the first part of this paper, we identify and illustrate these problems. We then present traits, a simple compositional model for structuring object-oriented programs. A trait is essentially a group of pure methods that serves as a building block for classes and is a primitive unit of code reuse. In this model, classes are composed from a set of traits by specifying glue code that connects the traits together and accesses the necessary state. We demonstrate how traits overcome the problems arising from the different variants of inheritance, we discuss how traits can be implemented effectively, and we summarize our experience applying traits to refactor an existing class hierarchy.

This research was partially supported by the National Science Foundation under award CCR-0098323.

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Author information

Authors and Affiliations

  1. Software Composition Group, University of Bern, Switzerland

    Nathanael Schärli, Stéphane Ducasse & Oscar Nierstrasz

  2. OGI School of Science & Engineering, Oregon Health and Science University,  

    Andrew P. Black

Authors
  1. Nathanael Schärli
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  2. Stéphane Ducasse
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  3. Oscar Nierstrasz
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  4. Andrew P. Black
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Editor information

Editors and Affiliations

  1. Microsoft Research,  

    Luca Cardelli

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Schärli, N., Ducasse, S., Nierstrasz, O., Black, A.P. (2003). Traits: Composable Units of Behaviour. In: Cardelli, L. (eds) ECOOP 2003 – Object-Oriented Programming. ECOOP 2003. Lecture Notes in Computer Science, vol 2743. Springer, Berlin, Heidelberg. https://doi.org/10.1007/978-3-540-45070-2_12

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  • DOI: https://doi.org/10.1007/978-3-540-45070-2_12

  • Publisher Name: Springer, Berlin, Heidelberg

  • Print ISBN: 978-3-540-40531-3

  • Online ISBN: 978-3-540-45070-2

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