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Futures And Promises
In computer science, future, promise, delay, and deferred refer to constructs used for synchronizing program execution in some concurrent programming languages. They describe an object that acts as a proxy for a result that is initially unknown, usually because the computation of its value is not yet complete. The term ''promise'' was proposed in 1976 by Daniel P. Friedman and David Wise, and Peter Hibbard called it ''eventual''. A somewhat similar concept ''future'' was introduced in 1977 in a paper by Henry Baker and Carl Hewitt. The terms ''future'', ''promise'', ''delay'', and ''deferred'' are often used interchangeably, although some differences in usage between ''future'' and ''promise'' are treated below. Specifically, when usage is distinguished, a future is a ''read-only'' placeholder view of a variable, while a promise is a writable, single assignment container which sets the value of the future. Notably, a future may be defined without specifying which specific pro ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Actor Model
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 (removing the need for lock-based synchronization). The actor model originated in 1973. It has been used both as a framework for a theoretical understanding of computation and as the theoretical basis for several practical implementations of concurrent systems. The relationship of the model to other work is discussed in actor model and process calculi. History According to Carl Hewitt, unlike previous models of computation, the actor model was inspired by physics, including general relativity and quantum mechanics. It was also influenced by the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Trait (computer Programming)
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. Rationale In object-oriented programming, behavior is sometimes shared between classes which are not related to each other. For example, many unrelated classes may have methods to serialize objects to JSON. Historically, there have been several approaches to solve this without duplicating the code in every class needing the behavior. Other approaches include multiple inheritance and mixins, but these have drawbacks: the behavior of the code may unexpectedly change if the order in which the mixins are applied is altered, or if new methods are added to the parent classes or mixins. Traits solve these problems by allowing classes to use the trait and get the desired behavior. If a class uses more than one trait, the order in which the traits are used does not matter. The methods provided by the traits have dire ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Object-oriented Programming
Object-oriented programming (OOP) is a programming paradigm based on the concept of "objects", which can contain data and code. The data is in the form of fields (often known as attributes or ''properties''), and the code is in the form of procedures (often known as ''methods''). A common feature of objects is that procedures (or methods) are attached to them and can access and modify the object's data fields. In this brand of OOP, there is usually a special name such as or used to refer to the current object. In OOP, computer programs are designed by making them out of objects that interact with one another. OOP languages are diverse, but the most popular ones are class-based, meaning that objects are instances of classes, which also determine their types. Many of the most widely used programming languages (such as C++, Java, Python, etc.) are multi-paradigm and they support object-oriented programming to a greater or lesser degree, typically in combination with imper ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Vrije Universiteit Brussel
The Vrije Universiteit Brussel (VUB) () is a Dutch and English-speaking research university located in Brussels, Belgium.The Vrije Universiteit Brussel is one of the five universities officially recognised by the Flemish Community, Flemish government. listof all official institutes of higher education in Flanders is maintained by the Flemish government. It has four campuses: Brussels Humanities, Science and Engineering Campus (in Elsene), Brussels Health Campus (in Jette), Brussels Technology Campus (in Anderlecht) and Brussels Photonics Campus (in Gooik). The Vrije Universiteit Brussel was formed in 1970 by the splitting of the Free University of Brussels (1834–1969), Free University of Brussels, which was founded in 1834 by the Flemish-Brussels lawyer Pierre-Théodore Verhaegen. The founder aimed to establish a university wiktionary:independent, independent from state and church, where academic freedom would be prevalent. This is today still reflected in the university's mo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Object-based Programming Languages
The term object-based language may be used in a technical sense to describe ''any'' programming language that uses the idea of encapsulating state and operations inside ''objects''. Object-based languages need not support inheritance or subtyping, but those that do are also termed ''object-oriented''. Object-based languages that do not support inheritance or subtyping are usually not considered to be true object-oriented languages. Examples of object-oriented languages, in rough chronological order, include Simula, Smalltalk, C++ (which object model is based on Simula's), Objective-C (which object model is based on Smalltalk's), Eiffel, Xojo (formerly REALbasic), Python, Ruby, Java, Visual Basic .NET, C#, and Fortran 2003. Examples of a language that is object-based, but not object-oriented are early versions of Ada, Visual Basic (VB), JavaScript, and Fortran 90. These languages all support the definition of an object as a data structure, but lack polymorphism and inheritance. In ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Experimental Programming Languages
An experiment is a procedure carried out to support or refute a hypothesis, or determine the efficacy or likelihood of something previously untried. Experiments provide insight into cause-and-effect by demonstrating what outcome occurs when a particular factor is manipulated. Experiments vary greatly in goal and scale but always rely on repeatable procedure and logical analysis of the results. There also exist natural experimental studies. A child may carry out basic experiments to understand how things fall to the ground, while teams of scientists may take years of systematic investigation to advance their understanding of a phenomenon. Experiments and other types of hands-on activities are very important to student learning in the science classroom. Experiments can raise test scores and help a student become more engaged and interested in the material they are learning, especially when used over time. Experiments can vary from personal and informal natural comparisons (e. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dynamic Programming Languages
Dynamics (from Greek δυναμικός ''dynamikos'' "powerful", from δύναμις ''dynamis'' "power") or dynamic may refer to: Physics and engineering * Dynamics (mechanics) ** Aerodynamics, the study of the motion of air ** Analytical dynamics, the motion of bodies as induced by external forces ** Brownian dynamics, the occurrence of Langevin dynamics in the motion of particles in solution ** File dynamics, stochastic motion of particles in a channel ** Flight dynamics, the science of aircraft and spacecraft design ** Fluid dynamics or ''hydrodynamics'', the study of fluid flow *** Computational fluid dynamics, a way of studying fluid dynamics using numerical methods ** Fractional dynamics, dynamics with integrations and differentiations of fractional orders ** Molecular dynamics, the study of motion on the molecular level ** Langevin dynamics, a mathematical model for stochastic dynamics ** Orbital dynamics, the study of the motion of rockets and spacecraft ** Quantum chro ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
"Hello, World!" Program
A "Hello, World!" program is generally a computer program that ignores any input and outputs or displays a message similar to "Hello, World!". A small piece of code in most general-purpose programming languages, this program is used to illustrate a language's basic syntax. "Hello, World!" programs are often the first a student learns to write in a given language, and they can also be used as a sanity check to ensure computer software intended to compile or run source code is correctly installed, and that its operator understands how to use it. History While small test programs have existed since the development of programmable computers, the tradition of using the phrase "Hello, World!" as a test message was influenced by an example program in the 1978 book ''The C Programming Language'', but there is no evidence that it originated there, and it is very likely it was used in BCPL beforehand (as below). The example program in that book prints "", and was inherited from a 1974 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
E Programming Language
E is an object-oriented programming language for secure distributed computing, created by Mark S. Miller, Dan Bornstein, Douglas Crockford, Chip Morningstar and others at Electric Communities in 1997. E is mainly descended from the concurrent language Joule and from Original-E, a set of extensions to Java for secure distributed programming. E combines message-based computation with Java-like syntax. A concurrency model based on event loops and promises ensures that deadlock can never occur. Philosophy The E language is designed with secure computing in mind; this is accomplished chiefly by strict adherence to the object-oriented computing model, which in its pure form has properties that support secure computing. The E language and its standard library employ a capability-based design philosophy throughout in order to help programmers build secure software and to enable software components to co-operate even if they don't fully trust each other. In E, object references se ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Concurrency (computer Science)
In computer science, concurrency is the ability of different parts or units of a program, algorithm, or problem to be executed out-of-order or in partial order, without affecting the outcome. This allows for parallel execution of the concurrent units, which can significantly improve overall speed of the execution in multi-processor and multi-core systems. In more technical terms, concurrency refers to the decomposability of a program, algorithm, or problem into order-independent or partially-ordered components or units of computation. According to Rob Pike, concurrency is the composition of independently executing computations, and concurrency is not parallelism: concurrency is about dealing with lots of things at once but parallelism is about doing lots of things at once. Concurrency is about structure, parallelism is about execution, concurrency provides a way to structure a solution to solve a problem that may (but not necessarily) be parallelizable. A number of mathema ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Android (operating System)
Android is a mobile operating system based on a modified version of the Linux kernel and other open-source software, designed primarily for touchscreen mobile devices such as smartphones and tablets. Android is developed by a consortium of developers known as the Open Handset Alliance and commercially sponsored by Google. It was unveiled in November 2007, with the first commercial Android device, the HTC Dream, being launched in September 2008. Most versions of Android are proprietary. The core components are taken from the Android Open Source Project (AOSP), which is free and open-source software (FOSS) primarily licensed under the Apache License. When Android is installed on devices, the ability to modify the otherwise free and open-source software is usually restricted, either by not providing the corresponding source code or by preventing reinstallation through technical measures, thus rendering the installed version proprietary. Most Android devices ship with additional ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
