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24th Annual ACM Conference on Object-Oriented Programming, Systems, Languages and Applications

作者： Malayeri, Donna Aldrich, Jonathan Carnegie Mellon Univ Pittsburgh PA 15213 USA

ISBN: (纸本)9781605587349

multiple inheritance has long been plagued with the "diamond" inheritance problem, leading to solutions that restrict expressiveness, such as mixins and traits. Instead, we address the diamond problem directly, considering two difficulties it causes ensuring a correct semantics for object initializers, and typechecking multiple dispatch in a modular fashion-the latter problem arising even with multiple interface inheritance. We show that previous solutions to these problems arts either unsatisfactory or cumbersome, and suggest a novel approach supporting multiple inheritance but forbidding diamond inheritance Expressiveness is retained through two features. a "requires" construct that provides a form of subtyping without inheritance (Inspired by Scala [40]), and a dynamically-dispatched "super" call similar to that found in traits. Through examples. we illustrate that inheritance diamonds can be eliminated via a combination of "requires" and ordinary inheritance. We provide a sound formal model for our language and demonstrate its modularity and expressiveness

关键词： multiple inheritance diamond problem multimethods modularity

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Empirical Assessment of Object-Oriented Implementations with multiple inheritance and Static Typing 09

Empirical Assessment of Object-Oriented Implementations with...

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24th Annual ACM Conference on Object-Oriented Programming, Systems, Languages and Applications

作者： Ducournau, Roland Morandat, Floreal Privat, Jean Univ Montpellier 2 LIRMM F-34095 Montpellier 5 France Univ Quebec Montreal Montreal PQ Canada

ISBN: (纸本)9781605587660

Object-oriented languages involve a threefold tradeoff between runtime efficiency, expressiveness (multiple inheritance), and modularity, i.e. open-world assumption (OWA). Runtime efficiency is conditioned by both the implementation technique and compilation scheme. The former specifies the data structures that support method invocation, attribute access and subtype testing. The latter consists of the production line of an executable from the source code. Many implementation techniques have been proposed and several compilation schemes can be considered from fully global compilation under the closed-world assumption (CWA) to separate compilation with dynamic loading under the OWA, with midway solutions. This article reviews a significant subset of possible combinations and presents a systematic, empirical comparison of their respective efficiencies with all other things being equal. The testbed consists of the PRM compiler that has been designed for this purpose. The considered techniques include C++ subobjects, coloring, perfect hashing, binary tree dispatch and caching. A variety of processors were considered. Qualitatively, these first results confirm the intuitive or theoretical abstract assessments of the tested approaches. As expected, efficiency increases as CWA strengthens. From a quantitative standpoint, the results are the first to precisely compare the efficiency of techniques that are closely associated with specific languages like C++ and EIFFEL. They also confirm that perfect hashing should be considered for implementing JAVA and. NET interfaces.

关键词： Experimentation Languages Measurement Performance binary tree dispatch closed-world assumption coloring downcast dynamic loading interfaces late binding method tables multiple inheritance multiple subtyping open-world assumption perfect hashing single inheritance subtype test type analysis virtual function tables

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Class Hierarchy Complementation: Soundly Completing a Partial Type Graph 13

Class Hierarchy Complementation: Soundly Completing a Partia...

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2013 ACM SIGPLAN International Conference on Object Oriented Programming Systems Languages

作者： Balatsouras, George Smaragdakis, Yannis Univ Athens Dept Informat Athens 15784 Greece

ISBN: (纸本)9781450323741

We present the problem of class hierarchy complementation: given a partially known hierarchy of classes together with subtyping constraints ("A has to be a transitive subtype of B") complete the hierarchy so that it satisfies all constraints. The problem has immediate practical application to the analysis of partial programs-e.g., it arises in the process of providing a sound handling of "phantom classes" in the Soot program analysis framework. We provide algorithms to solve the hierarchy complementation problem in the single inheritance and multiple inheritance settings. We also show that the problem in a language such as Java, with single inheritance but multiple subtyping and distinguished class vs. interface types, can be decomposed into separate single- and multiple-subtyping instances. We implement our algorithms in a tool, JPhantom, which complements partial Java bytecode programs so that the result is guaranteed to satisfy the Java verifier requirements. JPhantom is highly scalable and runs in mere seconds even for large input applications and complex constraints (with a maximum of 14s for a 19MB binary).

关键词： type hierarchy Java single inheritance multiple inheritance JPhantom bytecode engineering

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Class Hierarchy Complementation: Soundly Completing a Partial Type Graph

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ACM SIGPLAN NOTICES 2013年第10期48卷 515-532页

作者： Balatsouras, George Smaragdakis, Yannis Univ Athens Dept Informat Athens 15784 Greece

关键词： type hierarchy Java single inheritance multiple inheritance JPhantom bytecode engineering

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Separation Logic for multiple inheritance

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ELECTRONIC NOTES IN THEORETICAL COMPUTER SCIENCE 2008年第C期212卷 27-40页

作者： Luo, Chenguang Qin, Shengchao Univ Durham Dept Comp Sci Durham DH1 3LE England

As an extension to Floyd-Hoare logic, separation logic has been used to facilitate reasoning about imperative programs manipulating shared mutable data structures. Recently, it has also been extended to support modular reasoning in Java-like object-oriented languages where only single inheritance is allowed. In this paper we propose an extension of separation logic to support also the reasoning for multiple inheritance in C++ -like languages. To cater for multiple inheritance, we modified the standard storage model for separation logic in a way that the correct reference to a field or a method can be easily determined. On top of this storage model, a set of proof rules are proposed. Our verification system also provides basic support for behavioral subtyping.

关键词： multiple inheritance Separation Logic Verification

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A Graph-Based Formalism for Controlling Access to a Digital Library Ontology

A Graph-Based Formalism for Controlling Access to a Digital ...

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11th IFIP TC 8 International Conference on Computer Information Systems and Industrial Management (CISIM)

作者： Dasgupta, Subhasis Bagchi, Aditya Indian Stat Inst Kolkata 700108 India

ISBN: (纸本)9783642332609

This paper presents a graph-based formalism for an Ontology Based Access Control (OBAC) system applied to Digital Library (DL) ontology. It uses graph transformations, a graphical specification technique based on a generalization of classical string grammars to nonlinear structures. The proposed formalism provides an executable specification that exploits existing tools of graph grammar to verify the properties of a graph-based access control mechanism applicable to a digital library ontology description. It also provides a uniform specification for controlling access not only at the concept level but also at the level of the documents covered by the concepts including node obfuscation, if required.

关键词： Ontology Digital Library multiple inheritance OBAC

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Coloring, a versatile technique for implementing object-oriented languages

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SOFTWARE-PRACTICE & EXPERIENCE 2011年第6期41卷 627-659页

作者： Ducournau, Roland Univ Montpellier 2 LIRMM F-34000 Montpellier France CNRS F-34000 Montpellier France

Late binding and subtyping create run-time overhead for object-oriented languages. Dynamic typing and multiple inheritance create even more overhead. Static typing and single inheritance lead to two major invariants, of reference and position, that make the implementation as efficient as possible. Coloring is a technique that preserves these invariants for dynamic typing or multiple inheritance at minimal spatial cost. Coloring has been independently proposed for method invocation under the name of selector coloring, for subtype tests under the name of pack encoding, and for attribute access and object layout. This paper reviews a number of uses of coloring for optimizing object-oriented programming, generalizes them, and specifies several variations, such as bidirectional and n-directional coloring. Coloring is NP-hard, hence compilers that use it depend on heuristics. The paper describes two families of heuristics and presents some experimental results which indicate that coloring is both efficient and tractable and that bidirectional coloring gives the best results. Copyright (C) 2010 John Wiley & Sons, Ltd.

关键词： object-oriented programming multiple inheritance late binding object layout subtype testing virtual function tables

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Perfect class hashing and numbering for object-oriented implementation

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SOFTWARE-PRACTICE & EXPERIENCE 2011年第6期41卷 661-694页

作者： Ducournau, Roland Morandat, Floreal Univ Montpellier 2 LIRMM F-34000 Montpellier France CNRS F-34000 Montpellier France

Late binding and subtyping create run-time overhead for object-oriented languages, especially in the context of both multiple inheritance and dynamic loading, for instance for JAVA interfaces. In a previous article, we proposed a novel approach based on perfect hashing and truly constant-time hashtables for implementing subtype testing and method invocation in a dynamic loading setting. In this first study, we based our efficiency assessment on Driesen's abstract computational model for the time aspect, and on large-scale benchmarks for the space aspect. The conclusions were that the technique was promising but required further research in order to assess its scalability. This article presents some new results on perfect class hashing that enhance its interest. We propose and test both new hashing functions and an inverse problem that amounts to selecting the best class identifiers in order to minimize the overall hashtable size. This optimizing approach is proven to be optimal for single-inheritance hierarchies. Experiments within an extended testbed with random class loading and under cautious assumptions about what should be a sensible class-loading order show that perfect class hashing scales up gracefully, especially on JAVA-like multiple-subtyping hierarchies. Furthermore, perfect class hashing is implemented in the PRM compiler testbed, and compared here with the coloring technique, which amounts to maintaining the single-inheritance implementation in multiple inheritance. The overall conclusion is that the approach is efficient from both time and space standpoints with the bit-wise and hashing function. In contrast, the poor time efficiency of modulus hashing function on most processors is confirmed. Copyright (C) 2010 John Wiley & Sons, Ltd.

关键词： object-oriented programming dynamic loading multiple inheritance late binding subtype test perfect hashing

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A typed intermediate language for compiling multiple inheritance 07

A typed intermediate language for compiling multiple inherit...

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34th ACM SIGPLAN-SIGACT Symposium on Principles of Programming Languages

作者： Chen, Juan Microsoft Research

ISBN: (纸本)9781595935755

Type- preserving compilation can improve software reliability by generating code that can be verified independently of the compiler. Practical type-preserving compilation does not exist for languages with multiple inheritance. This paper presents E-MI, the first typed intermediate language to support practical compilation of a programming language with fully general multiple inheritance. The paper demonstrates the practicality of E-MI by showing that E-MI can be used to faithfully model standard implementation strategies of multiple inheritance for C++, the most widely-used programming language with general multiple inheritance.

关键词： languages typed intermediate language class and object encoding multiple inheritance

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Implementing Statically Typed Object-Oriented Programming Languages

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ACM COMPUTING SURVEYS 2011年第3期43卷 18-18页

作者： Ducournau, Roland LIRMM CNRS F-34392 Montpellier 5 France Univ Montpellier 2 F-34095 Montpellier 5 France

Object-oriented programming represents an original implementation issue due to its philosophy of making the program behavior depend on the dynamic type of objects. This is expressed by the late binding mechanism, aka message sending. The underlying principle is that the address of the actually called procedure is not statically determined at compile-time, but depends on the dynamic type of a distinguished parameter known as the receiver. A similar issue arises with attributes, because their position in the object layout may also depend on the object's dynamic type. Furthermore, subtyping introduces another original feature (i.e., runtime subtype checks). All three mechanisms need specific implementations and data structures. In static typing, late binding is generally implemented with so-called virtual function tables. These tables reduce method calls to pointers to functions via a small fixed number of extra indirections. It follows that object-oriented programming yields some overhead, as compared to the usual procedural languages. The different techniques and their resulting overhead depend on several parameters. First, inheritance and subtyping may be single or multiple, and even a mixing is possible, as in JAVA and. NET which present single inheritance for classes and multiple subtyping for interfaces. multiple inheritance is a well-known complication. Second, the production of executable programs may involve various schemes, from global compilation, which implies the closed-world assumption (CWA), as the whole program is known at compile time, to separate compilation and dynamic loading, where each program unit is compiled and loaded independently of any usage, hence under the open-world assumption (OWA). Global compilation is well-known to facilitate optimization. This article reviews the various implementation techniques available in static typing and in the three cases of single inheritance, multiple inheritance, and multiple subtyping. This language-indepe

关键词： Languages Measurement Performance Binary tree dispatch casting coloring downcast dynamic loading genericity late binding linking message sending method dispatch multiple inheritance pointer adjustment single inheritance static typing type analysis separate compilation virtual function tables C plus C# Eiffel Java PRM Theta

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