Agora is a reflective, prototype-based, object-oriented programming language that is based exclusively on message passing and not delegation. Agora was intended to show that even subject to that limit, it is possible to build a full object-oriented language that features inheritance, cloning and reflective operators.
The idea is that an object is fully encapsulated and can only be subject to message passing. But seen from the inside of the object, the object knows all about its own structures. It is therefore perfectly capable of cloning and extending itself. This is accomplished by special methods called cloning methods and mixin methods.
Agora98, the latest implementation of Agora, is done in Java and allows full access to all Java APIs, including the ability to create applets from within Agora98. From the language point of view, Agora98 is a considerable simplification of prior Agora versions.
Multiple inheritance is a feature of some object-oriented computer programming languages in which an object or class can inherit features from more than one parent object or parent class. It is distinct from single inheritance, where an object or class may only inherit from one particular object or class.
Prototype-based programming is a style of object-oriented programming in which behaviour reuse is performed via a process of reusing existing objects that serve as prototypes. This model can also be known as prototypal, prototype-oriented,classless, or instance-based programming.
In computer science, an object can be a variable, a data structure, a function, or a method. As regions of memory, they contain value and are referenced by identifiers.
In object-oriented programming languages, a mixin is a class that contains methods for use by other classes without having to be the parent class of those other classes. How those other classes gain access to the mixin's methods depends on the language. Mixins are sometimes described as being "included" rather than "inherited".
The fragile base class problem is a fundamental architectural problem of object-oriented programming systems where base classes (superclasses) are considered "fragile" because seemingly safe modifications to a base class, when inherited by the derived classes, may cause the derived classes to malfunction. The programmer cannot determine whether a base class change is safe simply by examining in isolation the methods of the base class.
Cecil is a pure object-oriented programming language that was developed by Craig Chambers at the University of Washington in 1992 to be part of the Vortex project there. Cecil has many similarities to other object-oriented languages, most notably Objective-C, Modula-3, and Self. The main goals of the project were extensibility, orthogonality, efficiency, and ease-of-use.
In object-oriented programming, delegation refers to evaluating a member of one object in the context of another original object. Delegation can be done explicitly, by passing the sending object to the receiving object, which can be done in any object-oriented language; or implicitly, by the member lookup rules of the language, which requires language support for the feature. Implicit delegation is the fundamental method for behavior reuse in prototype-based programming, corresponding to inheritance in class-based programming. The best-known languages that support delegation at the language level are Self, which incorporates the notion of delegation through its notion of mutable parent slots that are used upon method lookup on self calls, and JavaScript; see JavaScript delegation.
In computing, an interface is a shared boundary across which two or more separate components of a computer system exchange information. The exchange can be between software, computer hardware, peripheral devices, humans, and combinations of these. Some computer hardware devices, such as a touchscreen, can both send and receive data through the interface, while others such as a mouse or microphone may only provide an interface to send data to a given system.
Flavors, an early object-oriented extension to Lisp developed by Howard Cannon at the MIT Artificial Intelligence Laboratory for the Lisp machine and its programming language Lisp Machine Lisp, was the first programming language to include mixins. Symbolics used it for its Lisp machines, and eventually developed it into New Flavors; both the original and new Flavors were message passing OO models. It was hugely influential in the development of the Common Lisp Object System (CLOS).
The actor model in computer science is a mathematical model of concurrent computation that treats actor as the universal primitive of concurrent computation. In response to a message it receives, an actor can: make local decisions, create more actors, send more messages, and determine how to respond to the next message received. Actors may modify their own private state, but can only affect each other indirectly through messaging.
In object-oriented programming, inheritance is the mechanism of basing an object or class upon another object or class, retaining similar implementation. Also defined as deriving new classes from existing ones such as super class or base class and then forming them into a hierarchy of classes. In most class-based object-oriented languages, an object created through inheritance, a "child object", acquires all the properties and behaviors of the "parent object", with the exception of: constructors, destructor, overloaded operators and friend functions of the base class. Inheritance allows programmers to create classes that are built upon existing classes, to specify a new implementation while maintaining the same behaviors, to reuse code and to independently extend original software via public classes and interfaces. The relationships of objects or classes through inheritance give rise to a directed acyclic graph.
In computer programming, a trait is a concept used in object-oriented programming which represents a set of methods that can be used to extend the functionality of a class.
Actor-Based Concurrent Language (ABCL) is a family of programming languages, developed in Japan in the 1980s and 1990s.
AmbientTalk is an experimental object-oriented distributed programming language developed at the Programming Technology Laboratory at the Vrije Universiteit Brussel, Belgium. The language is primarily targeted at writing programs deployed in mobile ad hoc networks.
In computing, subject-oriented programming is an object-oriented software paradigm in which the state (fields) and behavior (methods) of objects are not seen as intrinsic to the objects themselves, but are provided by various subjective perceptions ("subjects") of the objects. The term and concepts were first published in September 1993 in a conference paper which was later recognized as being one of the three most influential papers to be presented at the conference between 1986 and 1996. As illustrated in that paper, an analogy is made with the contrast between the philosophical views of Plato and Kant with respect to the characteristics of "real" objects, but applied to software ones. For example, while we may all perceive a tree as having a measurable height, weight, leaf-mass, etc., from the point of view of a bird, a tree may also have measures of relative value for food or nesting purposes, or from the point of view of a tax-assessor, it may have a certain taxable value in a given year. Neither the bird's nor the tax-assessor's additional state information need be seen as intrinsic to the tree, but are added by the perceptions of the bird and tax-assessor, and from Kant's analysis, the same may be true even of characteristics we think of as intrinsic.
The expression problem is a challenge problem in programming languages that concerns the extensibility and modularity of statically typed data abstractions. The goal is to define a data abstraction that is extensible both in its representations and its behaviors, where one can add new representations and new behaviors to the data abstraction, without recompiling existing code, and while retaining static type safety. It exposed deficiencies in programming paradigms and programming languages, and it is still not definitively solved, although there are many proposed solutions.
Composition over inheritance in object-oriented programming (OOP) is the principle that classes should achieve polymorphic behavior and code reuse by their composition rather than inheritance from a base or parent class. This is an often-stated principle of OOP, such as in the influential book Design Patterns (1994).
Object-oriented programming (OOP) is a programming paradigm based on the concept of "objects", which can contain data and code: data in the form of fields, and code, in the form of procedures.
Object schizophrenia or self schizophrenia is a complication arising from delegation and related techniques in object-oriented programming, where self
/this
can refer to more than one object. By way of metaphor with the public confusion of dissociative identity disorder with the psychiatric diagnosis of schizophrenia, the former being associated with "split personalities," this configuration is called object schizophrenia or self schizophrenia in object-oriented programming.
The composition filters model denotes a modular extension to the conventional object model. It provides a solution for a wide range of problems in the construction of large and complex applications. Most notably, one implementation of composition filters provides an abstraction layer for message-passing systems.