Immutable Objects for a Java-Like Language

Haack, Christian; Poll, Erik; Schäfer, Jan; Schubert, Aleksy

doi:10.1007/978-3-540-71316-6_24

Cited by 25 publications

(21 citation statements)

References 15 publications

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“…Following our earlier work [18], we support the distinction between mutable and im mutable objects through access qualifiers on types:…”

Section: Specifying Immutability With Type Qualifiersmentioning

confidence: 95%

“…Specifically, it must guarantee that instances of immutable classes encapsulate their representation objects and that their object constructors do not leak self-references. In our earlier paper [18], we enforced these properties using two typebased confinement techniques (in addition to the access qualifiers Rd and RdWr), namely a dedicated ownership type system for enforcing encapsulation of representation ob jects, and so-called anonymous methods [32] for confining self-references during ob ject construction. Unfortunately, the resulting type system was more complex than one would desire.…”

Section: Object Confinement With Qualifier-polymorphic Methodsmentioning

confidence: 99%

“…Some of the above type systems require that initialization takes place inside object constructors [13,18,34]. Unfortunately, this does not really simplify matters because object construc tors in Java-like languages can contain arbitrary code (which may, for instance, leak self-references or call dynamically dispatched methods).…”

Section: Flexible Object Initialization With Stack-local Regionsmentioning

confidence: 99%

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Type-Based Object Immutability with Flexible Initialization

Haack

Poll

2009

Lecture Notes in Computer Science

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Abstract. We present a type system for checking object immutability, read-only references, and class immutability in an open or closed world. To allow object initialization outside object constructors (which is often needed in practice), im mutable objects are initialized in lexically scoped regions. The system is simple and direct; its only type qualifiers specify immutability properties. No auxiliary annotations, e.g., ownership types, are needed, yet good support for deep im mutability is provided. To express object confinement, as required for class im mutability in an open world, we use qualifier polymorphism. The system has two versions: one with explicit specification commands that delimit the object initialization phase, and one where such commands are im plicit and inferred. In the latter version, all annotations are compatible with Java's extended annotation syntax, as proposed in JSR 308.

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“…Following our earlier work [18], we support the distinction between mutable and im mutable objects through access qualifiers on types:…”

Section: Specifying Immutability With Type Qualifiersmentioning

confidence: 95%

Section: Object Confinement With Qualifier-polymorphic Methodsmentioning

confidence: 99%

Section: Flexible Object Initialization With Stack-local Regionsmentioning

confidence: 99%

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Type-Based Object Immutability with Flexible Initialization

Haack

Poll

2009

Lecture Notes in Computer Science

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“…Immutability is present in other type systems (e.g., Javari [Tschantz and Ernst 2005]; Jimuva [Haack et al 2007]; IGJ [Zibin et al 2007]; and Joe 3 [Östlund et al 2008]) and in a dynamic encoding of ownership called frozen objects [Leino et al 2008]. Investigating the combination with Universe types is interesting future work.…”

Section: Read-only References and Immutabilitymentioning

confidence: 99%

Separating ownership topology and encapsulation with generic universe types

Dietl

Drossopoulou

Müller

2011

ACM Trans. Program. Lang. Syst.

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Ownership is a powerful concept to structure the object store and to control aliasing and modifications of objects. This article presents an ownership type system for a Java-like programming language with generic types.Like our earlier Universe type system, Generic Universe Types structure the heap hierarchically. In contrast to earlier work, we separate the enforcement of an ownership topology from an encapsulation system. The topological system uses an existential modifier to express that no ownership information is available statically. On top of the topological system, we build an encapsulation system that enforces the owner-as-modifier discipline. This discipline does not restrict aliasing, but requires modifications of an object to be initiated by its owner. This allows owner objects to control state changes of owned objects-for instance, to maintain invariants. Separating the topological system from the encapsulation system allows for a cleaner formalization, separation of concerns, and simpler reuse of the individual systems in different contexts.

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“…Immutability is enforced through compiler checks in addition to ownership types, an approach similar to other immutable object schemes [4,15]. The tool enforces the following requirements on classes declared as immutable:…”

Section: Immutable Typesmentioning

confidence: 99%

Deadlock freedom through object ownership

Kerfoot

McKeever

Torshizi

2009

International Workshop on Aliasing, Confinement and Ownership in Object-Oriented Programming

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Active objects are an attractive method of introducing concurrency into Java-like languages by decoupling method execution from invocation. In this paper, we show how ownership is used in the Java [14] subset language CoJava [17] to prevent deadlock associated with active object method calls. This approach builds on existing type-based approaches that eliminates data races and data-based deadlock in concurrent systems. The novel addition is the use of ownership to organize active objects, thus preventing deadlock from arising when objects are allowed to block awaiting responses from others.Typechecking is used to prevent threads from sharing mutable data, thus CoJava is free of data races and data-based deadlock. Behavioural deadlock is prevented by the use of promise objects which prevent clients from blocking indefinitely while awaiting responses. Ownership imposes a hierarchy on active objects; this allows owners to safely block while waiting for responses from owned objects. The paper also discusses the implications of this approach to specification with JML, formal reasoning about programs, and the consequences to runtime assertion checking.

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Immutable Objects for a Java-Like Language

Cited by 25 publications

References 15 publications

Type-Based Object Immutability with Flexible Initialization

Type-Based Object Immutability with Flexible Initialization

Separating ownership topology and encapsulation with generic universe types

Deadlock freedom through object ownership

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