Article

A virtual class calculus

Authors:

Klaus Ostermann,

William R. CookAuthors Info & Claims

POPL '06: Conference record of the 33rd ACM SIGPLAN-SIGACT symposium on Principles of programming languages

Pages 270 - 282

https://doi.org/10.1145/1111037.1111062

Published: 11 January 2006 Publication History

Abstract

Virtual classes are class-valued attributes of objects. Like virtual methods, virtual classes are defined in an object's class and may be redefined within subclasses. They resemble inner classes, which are also defined within a class, but virtual classes are accessed through object instances, not as static components of a class. When used as types, virtual classes depend upon object identity -- each object instance introduces a new family of virtual class types. Virtual classes support large-scale program composition techniques, including higher-order hierarchies and family polymorphism. The original definition of virtual classes in BETA left open the question of static type safety, since some type errors were not caught until runtime. Later the languages Caesar and gbeta have used a more strict static analysis in order to ensure static type safety. However, the existence of a sound, statically typed model for virtual classes has been a long-standing open question. This paper presents a virtual class calculus, VC, that captures the essence of virtual classes in these full-fledged programming languages. The key contributions of the paper are a formalization of the dynamic and static semantics of VC and a proof of the soundness of VC.

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https://dl.acm.org/doi/10.1145/3689782
Kravchuk-Kirilyuk AFeng GIskander JZhang YAmin N(2024)Persimmon: Nested Family Polymorphism with Extensible Variant TypesProceedings of the ACM on Programming Languages10.1145/36498368:OOPSLA1(698-724)Online publication date: 29-Apr-2024
https://dl.acm.org/doi/10.1145/3649836
Jin EAmin NZhang Y(2023)Extensible Metatheory Mechanization via Family PolymorphismProceedings of the ACM on Programming Languages10.1145/35912867:PLDI(1608-1632)Online publication date: 6-Jun-2023
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Index Terms

A virtual class calculus
1. Software and its engineering
  1. Software notations and tools
    1. General programming languages
      1. Language features
        Classes and objects
        Inheritance
        Polymorphism
2. Theory of computation
  1. Semantics and reasoning
    1. Program constructs
      1. Object oriented constructs
      2. Type structures
    2. Program semantics
      1. Operational semantics

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cover image ACM Conferences

POPL '06: Conference record of the 33rd ACM SIGPLAN-SIGACT symposium on Principles of programming languages

January 2006

432 pages

ISBN:1595930272

DOI:10.1145/1111037

General Chair:
Greg Morrisett
Harvard University, USA
,
Program Chair:
Simon Peyton Jones
Microsoft Research, UK

ACM SIGPLAN Notices Volume 41, Issue 1
Proceedings of the 2006 POPL Conference
January 2006
421 pages
ISSN:0362-1340
EISSN:1558-1160
DOI:10.1145/1111320
Issue’s Table of Contents

Copyright © 2006 ACM.

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Published: 11 January 2006

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January 11 - 13, 2006

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https://dl.acm.org/doi/10.1145/3689782
Kravchuk-Kirilyuk AFeng GIskander JZhang YAmin N(2024)Persimmon: Nested Family Polymorphism with Extensible Variant TypesProceedings of the ACM on Programming Languages10.1145/36498368:OOPSLA1(698-724)Online publication date: 29-Apr-2024
https://dl.acm.org/doi/10.1145/3649836
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Dagnino FBono VZucca EDezani-Ciancaglini M(2020)Soundness Conditions for Big-Step SemanticsProgramming Languages and Systems10.1007/978-3-030-44914-8_7(169-196)Online publication date: 27-Apr-2020
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