scholarly journals FHJ: A formal model for hierarchical dispatching and overriding

2020 ◽  
Author(s):  
Y Wang ◽  
H Zhang ◽  
BCDS Oliveira ◽  
Marco Servetto
Keyword(s):  
Common Ancestor ◽  
Formal Model ◽  
Object Oriented ◽  
Object Oriented Programming ◽  
Extensive Literature ◽  
Multiple Inheritance ◽  
New Model ◽  
Dynamic Type ◽  
Inheritance Hierarchy ◽  
Type Information

© Yanlin Wang, Haoyuan Zhang, Bruno C. d. S. Oliveira, and Marco Servetto. Multiple inheritance is a valuable feature for Object-Oriented Programming. However, it is also tricky to get right, as illustrated by the extensive literature on the topic. A key issue is the ambiguity arising from inheriting multiple parents, which can have conflicting methods. Numerous existing work provides solutions for conflicts which arise from diamond inheritance: i.e. conflicts that arise from implementations sharing a common ancestor. However, most mechanisms are inadequate to deal with unintentional method conflicts: conflicts which arise from two unrelated methods that happen to share the same name and signature. This paper presents a new model called Featherweight Hierarchical Java (FHJ) that deals with unintentional method conflicts. In our new model, which is partly inspired by C++, conflicting methods arising from unrelated methods can coexist in the same class, and hierarchical dispatching supports unambiguous lookups in the presence of such conflicting methods. To avoid ambiguity, hierarchical information is employed in method dispatching, which uses a combination of static and dynamic type information to choose the implementation of a method at run-time. Furthermore, unlike all existing inheritance models, our model supports hierarchical method overriding: that is, methods can be independently overridden along the multiple inheritance hierarchy. We give illustrative examples of our language and features and formalize FHJ as a minimal Featherweight-Java style calculus.

scholarly journals FHJ: A formal model for hierarchical dispatching and overriding

2020 ◽  
Author(s):  
Y Wang ◽  
H Zhang ◽  
BCDS Oliveira ◽  
Marco Servetto
Keyword(s):  
Common Ancestor ◽  
Formal Model ◽  
Object Oriented ◽  
Object Oriented Programming ◽  
Extensive Literature ◽  
Multiple Inheritance ◽  
New Model ◽  
Dynamic Type ◽  
Inheritance Hierarchy ◽  
Type Information

© Yanlin Wang, Haoyuan Zhang, Bruno C. d. S. Oliveira, and Marco Servetto. Multiple inheritance is a valuable feature for Object-Oriented Programming. However, it is also tricky to get right, as illustrated by the extensive literature on the topic. A key issue is the ambiguity arising from inheriting multiple parents, which can have conflicting methods. Numerous existing work provides solutions for conflicts which arise from diamond inheritance: i.e. conflicts that arise from implementations sharing a common ancestor. However, most mechanisms are inadequate to deal with unintentional method conflicts: conflicts which arise from two unrelated methods that happen to share the same name and signature. This paper presents a new model called Featherweight Hierarchical Java (FHJ) that deals with unintentional method conflicts. In our new model, which is partly inspired by C++, conflicting methods arising from unrelated methods can coexist in the same class, and hierarchical dispatching supports unambiguous lookups in the presence of such conflicting methods. To avoid ambiguity, hierarchical information is employed in method dispatching, which uses a combination of static and dynamic type information to choose the implementation of a method at run-time. Furthermore, unlike all existing inheritance models, our model supports hierarchical method overriding: that is, methods can be independently overridden along the multiple inheritance hierarchy. We give illustrative examples of our language and features and formalize FHJ as a minimal Featherweight-Java style calculus.

scholarly journals Object Cloning for Ownership Systems

2021 ◽  
Author(s):  
◽  
Paley Guangping Li
Keyword(s):  
Comparative Analysis ◽  
Programming Languages ◽  
Formal Model ◽  
Operational Semantics ◽  
Type System ◽  
Object Oriented ◽  
Object Oriented Programming ◽  
Constraint System ◽  
Existential Quantification ◽  
Ownership Types

<p>Modern object-oriented programming languages frequently need the ability to clone, duplicate, and copy objects. The usual approaches taken by languages are rudimentary, primarily because these approaches operate with little understanding of the object being cloned. Deep cloning naively copies every object that has a reachable reference path from the object being cloned, even if the objects being copied have no innate relationship with that object. For more sophisticated cloning operations, languages usually only provide the capacity for programmers to define their own cloning operations for specific objects, and with no help from the type system.  Sheep cloning is an automated operation that clones objects by leveraging information about those objects’ structures, which the programmer imparts into their programs with ownership types. Ownership types are a language mechanism that defines an owner for every object in the program. Ownership types create a hierarchical structure for the heap.  In this thesis, we construct an extensible formal model for an object-oriented language with ownership types (Core), and use it to explore different formalisms of sheep cloning. We formalise three distinct operational semantics of sheep cloning, and for each approach we include proofs or proof outlines where appropriate, and provide a comparative analysis of each model’s benefits. Our main contribution is the descripSC formal model of sheep cloning and its proof of type soundness.  The second contribution of this thesis is the formalism of Mojo-jojo, a multiple ownership system that includes existential quantification over types and context parameters, along with a constraint system for context parameters. We prove type soundness for Mojo-jojo. Multiple ownership is a mechanism which allows objects to have more than one owner. Context parameters in Mojo-jojo can use binary operators such as: intersection, union, and disjointness.</p>

scholarly journals Generic Ownership: a Practical Approach to Ownership and Confinement in Object-Oriented  Programming Languages

2021 ◽  
Author(s):  
◽  
Alex Potanin
Keyword(s):  
Programming Languages ◽  
Object Oriented ◽  
Object Oriented Programming ◽  
Minimal Extension ◽  
Language Implementation ◽  
The Core ◽  
Simple Formalism ◽  
Functional Setting ◽  
Type Information ◽  
Ownership Types

<p>Modern object-oriented programming languages support many techniques that simplify the work of a programmer. Among them is generic types: the ability to create generic descriptions of algorithms and object structures that will be automatically specialised by supplying the type information when they are used. At the same time, object-oriented technologies still suffer from aliasing: the case of many objects in a program's memory referring to the same object via different references. Ownership types enforce encapsulation in object-oriented programs by ensuring that objects cannot be referred to from the outside of the object(s) that own them. Existing ownership programming languages either do not support generic types or attempt to add them on top of ownership restrictions. The goal of this work is to bring object ownership into mainstream object-oriented programming languages. This thesis presents Generic Ownership which provides perobject ownership on top of a generic imperative language. Surprisingly, the resulting system not only provides ownership guarantees comparable to the established systems, but also requires few additional language mechanisms to achieve them due to full reuse of generic types. In this thesis I formalise the core of Generic Ownership, highlighting that the restriction of this calls, owner preservation over subtyping, and appropriate owner nesting are the only necessary requirements for ownership. I describe two formalisms: (1) a simple formalism, capturing confinement in a functional setting, and (2) a complete formalism, providing a way for Generic Ownership to support both deep and shallow variations of ownership types. I support the formal work by describing how the Ownership Generic Java (OGJ) language is implemented as a minimal extension to Java 5. OGJ is the first publicly available language implementation that supports ownership, confinement, and generic types at the same time. I demonstrate OGJ in practice: show how to use OGJ to write programs and provide insights into the implementations of Generic Ownership.</p>

A theory of mixin modules: basic and derived operators

1998 ◽  
Vol 8 (4) ◽  
pp. 401-446 ◽  
Author(s):  
DAVIDE ANCONA ◽  
ELENA ZUCCA
Keyword(s):  
Formal Model ◽  
Composition Operators ◽  
Object Oriented ◽  
Object Oriented Programming ◽  
Basic Composition ◽  
Semantic Framework ◽  
Core Language

Mixins are modules in which some components are deferred, that is, their definition has to be provided by another module. Moreover, in contrast to parameterized modules (like ML functors), mixin modules can be mutually dependent and their composition supports the redefinition of components (overriding). In this paper, we present a formal model of mixins and their basic composition operators. These operators can be viewed as a kernel language with clean semantics in which one can express more complex operators of existing modular languages, including variants of inheritance in object-oriented programming. Our formal model is given in an ‘institution independent’ way, that is, it is parameterized by the semantic framework modelling the underlying core language.

scholarly journals Object Cloning for Ownership Systems

2021 ◽  
Author(s):  
◽  
Paley Guangping Li
Keyword(s):  
Comparative Analysis ◽  
Programming Languages ◽  
Formal Model ◽  
Operational Semantics ◽  
Type System ◽  
Object Oriented ◽  
Object Oriented Programming ◽  
Constraint System ◽  
Existential Quantification ◽  
Ownership Types

<p>Modern object-oriented programming languages frequently need the ability to clone, duplicate, and copy objects. The usual approaches taken by languages are rudimentary, primarily because these approaches operate with little understanding of the object being cloned. Deep cloning naively copies every object that has a reachable reference path from the object being cloned, even if the objects being copied have no innate relationship with that object. For more sophisticated cloning operations, languages usually only provide the capacity for programmers to define their own cloning operations for specific objects, and with no help from the type system.  Sheep cloning is an automated operation that clones objects by leveraging information about those objects’ structures, which the programmer imparts into their programs with ownership types. Ownership types are a language mechanism that defines an owner for every object in the program. Ownership types create a hierarchical structure for the heap.  In this thesis, we construct an extensible formal model for an object-oriented language with ownership types (Core), and use it to explore different formalisms of sheep cloning. We formalise three distinct operational semantics of sheep cloning, and for each approach we include proofs or proof outlines where appropriate, and provide a comparative analysis of each model’s benefits. Our main contribution is the descripSC formal model of sheep cloning and its proof of type soundness.  The second contribution of this thesis is the formalism of Mojo-jojo, a multiple ownership system that includes existential quantification over types and context parameters, along with a constraint system for context parameters. We prove type soundness for Mojo-jojo. Multiple ownership is a mechanism which allows objects to have more than one owner. Context parameters in Mojo-jojo can use binary operators such as: intersection, union, and disjointness.</p>

Higher-order intersection types and multiple inheritance

1996 ◽  
Vol 6 (5) ◽  
pp. 469-501 ◽  
Author(s):  
Adriana B. Compagnoni ◽  
Benjamin C. Pierce
Keyword(s):  
Structural Properties ◽  
Object Oriented ◽  
Natural Generalization ◽  
Higher Order ◽  
Object Oriented Programming ◽  
Equivalence Relations ◽  
Semantic Model ◽  
Multiple Inheritance ◽  
Intersection Types ◽  
Partial Equivalence Relations

We study a natural generalization of SystemFωwith intersection types, establishing basic structural properties and constructing a semantic model based on partial equivalence relations to prove the soundness of typing. As an application of this calculus, we define a simple typed model of object-oriented programming with multiple inheritance.

scholarly journals Emulating Multiple Inheritance in Fortran 2003/2008

2015 ◽  
Vol 2015 ◽  
pp. 1-7
Author(s):  
Karla Morris
Keyword(s):  
Design Pattern ◽  
High Performance ◽  
Object Oriented ◽  
Object Oriented Programming ◽  
Multiple Inheritance ◽  
C Programming ◽  
Class Hierarchies ◽  
Fortran 90 ◽  
Performance Computing ◽  
Intrinsic Feature

Although the high-performance computing (HPC) community increasingly embraces object-oriented programming (OOP), most HPC OOP projects employ the C++ programming language. Until recently, Fortran programmers interested in mining the benefits of OOP had to emulate OOP in Fortran 90/95. The advent of widespread compiler support for Fortran 2003 now facilitates explicitly constructing object-oriented class hierarchies via inheritance and leveraging related class behaviors such as dynamic polymorphism. Although C++ allows a class to inherit from multiple parent classes, Fortran and several other OOP languages restrict or prohibit explicit multiple inheritance relationships in order to circumvent several pitfalls associated with them. Nonetheless, what appears as an intrinsic feature in one language can be modeled as a user-constructed design pattern in another language. The present paper demonstrates how to apply the facade structural design pattern to support a multiple inheritance class relationship in Fortran 2003. The design unleashes the power of the associated class relationships for modeling complicated data structures yet avoids the ambiguities that plague some multiple inheritance scenarios.

Inheritance in Programming Languages

2011 ◽  
pp. 2042-2047
Author(s):  
Krishnaprasad Thirunarayan
Keyword(s):  
Programming Languages ◽  
Common Sense ◽  
Effective Means ◽  
Type System ◽  
Object Oriented ◽  
Object Oriented Programming ◽  
Multiple Inheritance ◽  
Contrast Method ◽  
Compare And Contrast ◽  
Object Oriented Databases

Inheritance is a powerful concept employed in computer science, especially in artificial intelligence (AI), object-oriented programming (OOP), and object-oriented databases (OODB). In the field of AI, inheritance has been primarily used as a concise and effective means of representing and reasoning with common-sense knowledge (Thirunarayan, 1995). In programming languages and databases, inheritance has been used for the purpose of sharing data and methods, and for enabling modularity of software (re)use and maintenance (Lakshmanan & Thirunarayan, 1998). In this chapter, we present various design choices for incorporating inheritance into programming languages from an application programmer’s perspective. In contrast with the language of mathematics, which is mature and well-understood, the embodiment of object-oriented concepts and constructs in a concrete programming language is neither fixed nor universally accepted. We exhibit programs with similar syntax in different languages that have very different semantics, and different looking programs that are equivalent. We compare and contrast method inheritance, interaction of type system with method binding, constructs for method redefinition, and their implementation in widely used languages such as C++ (Stroustrup, 1997), Java (Arnold, Gosling, & Holmes, 2005), and C# (Hejlsberg, Wiltamuth, & Golde, 2006), to illustrate subtle issues of interest to programmers. Finally, we discuss multiple inheritance briefly.

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