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Poltergeist (computer Science)
In computer programming, a poltergeist (or gypsy wagon) is a short-lived, typically stateless object used to perform initialization or to invoke methods in another, more permanent class. It is considered an anti-pattern. The original definition is by Michael Akroyd at the 1996 Object World West Conference: A poltergeist can often be identified by its name; they are often called "manager_", "controller_", "supervisor", "start_process", etc. Sometimes, poltergeist classes are created because the programmer anticipated the need for a more complex architecture. For example, a poltergeist arises if the same method acts as both the ''client'' and ''invoker'' in a command pattern, and the programmer anticipates separating the two phases. However, this more complex architecture may actually never materialize. Poltergeists should not be confused with long-lived, state-bearing objects of a pattern such as model–view–controller, or tier-separating patterns such as business delegate p ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Computer Programming
Computer programming or coding is the composition of sequences of instructions, called computer program, programs, that computers can follow to perform tasks. It involves designing and implementing algorithms, step-by-step specifications of procedures, by writing source code, code in one or more programming languages. Programmers typically use high-level programming languages that are more easily intelligible to humans than machine code, which is directly executed by the central processing unit. Proficient programming usually requires expertise in several different subjects, including knowledge of the Domain (software engineering), application domain, details of programming languages and generic code library (computing), libraries, specialized algorithms, and Logic#Formal logic, formal logic. Auxiliary tasks accompanying and related to programming include Requirements analysis, analyzing requirements, Software testing, testing, debugging (investigating and fixing problems), imple ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
State (computer Science)
In information technology and computer science, a system is described as stateful if it is designed to remember preceding events or user interactions; the remembered information is called the state of the system. The set of states a system can occupy is known as its state space. In a discrete system, the state space is countable and often finite. The system's internal behaviour or interaction with its environment consists of separately occurring individual actions or events, such as accepting input or producing output, that may or may not cause the system to change its state. Examples of such systems are digital logic circuits and components, automata and formal language, computer programs, and computers. The output of a digital circuit or deterministic computer program at any time is completely determined by its current inputs and its state. Digital logic circuit state Digital logic circuits can be divided into two types: combinational logic, whose output signals a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Anti-pattern
An anti-pattern in software engineering, project management, and business processes is a common response to a recurring problem that is usually ineffective and risks being highly counterproductive. The term, coined in 1995 by computer programmer Andrew Koenig (programmer), Andrew Koenig, was inspired by the book ''Design Patterns'' (which highlights a number of design patterns in software development that its authors considered to be highly reliable and effective) and first published in his article in the ''Journal of Object-Oriented Programming''. A further paper in 1996 presented by Michael Ackroyd at the Object World West Conference also documented anti-patterns. It was, however, the 1998 book ''AntiPatterns'' that both popularized the idea and extended its scope beyond the field of software design to include software architecture and project management. Other authors have extended it further since to encompass environmental, organizational, and cultural anti-patterns. Definiti ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Vardo (Romani Wagon)
A vardo (also Romani wag(g)on, Gypsy wagon, living wagon, caravan, van and house-on-wheels) is a four-wheeled horse-drawn vehicle traditionally used by travelling Romanichal as their home. The name ''vardo'' is a Romani language, Romani term believed to have originated from the Ossetian language, Ossetic ''wærdon'' meaning cart or carriage. It is pulled by a single horse in shafts, sometimes with a second horse (called a ''sider'' or ''sideliner'') hitched on its right side outside the shafts to help pull heavier loads or assist in pulling up a hill. The vehicle is typically highly decorated, intricately carved, brightly painted, and even gilded. The Romanichal tradition of the vardo is seen as a high cultural point of both artistic design and a masterpiece of woodcrafter's art. The heyday of the caravan lasted for roughly 70 years, from the mid-nineteenth century through the first two decades of the twentieth century. Not used for year-round living today, they are shown at the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Poltergeist
In German folklore and ghostlore, a poltergeist ( or ; ; or ) is a type of ghost or spirit that is responsible for physical disturbances, such as loud noises and objects being moved or destroyed. Most claims or fictional descriptions of poltergeists show them as being capable of pinching, biting, hitting, and tripping people. They are also depicted as capable of the movement or levitation of objects such as furniture and cutlery, or noises such as knocking on doors. Foul smells are also associated with poltergeist occurrences, as well as spontaneous fires and different electrical issues such as flickering lights. These manifestations have been recorded in many cultures and countries, including Brazil, Australia, the United States, Japan and most European nations. The first recorded cases date back to the 1st century. Skeptics explain poltergeists as juvenile tricksters fooling credulous adults. Etymology The word ''poltergeist'' comes from the German language words and ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Programmer
A programmer, computer programmer or coder is an author of computer source code someone with skill in computer programming. The professional titles Software development, ''software developer'' and Software engineering, ''software engineer'' are used for jobs that require a programmer. Identification Sometimes a programmer or job position is identified by the language used or target platform. For example, assembly language, assembly programmer, web developer. Job title The job titles that include programming tasks have differing connotations across the computer industry and to different individuals. The following are notable descriptions. A ''software developer'' primarily implements software based on specifications and fixes Software bug, bugs. Other duties may include code review, reviewing code changes and software testing, testing. To achieve the required skills for the job, they might obtain a computer science or associate degree, associate degree, attend a Cod ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Command Pattern
In object-oriented programming, the command pattern is a Behavioral pattern, behavioral Design pattern (computer science), design pattern in which an object is used to Information hiding, encapsulate all information needed to perform an action or trigger an event at a later time. This information includes the method name, the object that owns the method and values for the method parameters. Four terms always associated with the command pattern are ''command'', ''receiver'', ''invoker'' and ''client''. A ''command'' object knows about ''receiver'' and invokes a method of the receiver. Values for parameters of the receiver method are stored in the command. The receiver object to execute these methods is also stored in the command object by Object composition#Aggregation, aggregation. The ''receiver'' then does the work when the execute() method in ''command'' is called. An ''invoker'' object knows how to execute a command, and optionally does bookkeeping about the command execution. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Software Design Pattern
In software engineering, a software design pattern or design pattern is a general, reusable solution to a commonly occurring problem in many contexts in software design. A design pattern is not a rigid structure to be transplanted directly into source code. Rather, it is a description or a template for solving a particular type of problem that can be deployed in many different situations. Design patterns can be viewed as formalized best practices that the programmer may use to solve common problems when designing a software application or system. Object-oriented design patterns typically show relationships and interactions between classes or objects, without specifying the final application classes or objects that are involved. Patterns that imply mutable state may be unsuited for functional programming languages. Some patterns can be rendered unnecessary in languages that have built-in support for solving the problem they are trying to solve, and object-oriented patterns are no ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Model–view–controller
Model–view–controller (MVC) is a software architectural pattern commonly used for developing user interfaces that divides the related program logic into three interconnected elements. These elements are: * the model, the internal representations of information * the view, the interface that presents information to and accepts it from the user * the controller, the software linking the two. Traditionally used for desktop graphical user interfaces (GUIs), this pattern became popular for designing web applications. Popular programming languages have MVC frameworks that facilitate the implementation of the pattern. __TOC__ History One of the seminal insights in the early development of graphical user interfaces, MVC became one of the first approaches to describe and implement software constructs in terms of their responsibilities. Trygve Reenskaug created MVC while working on Smalltalk-79 as a visiting scientist at the Xerox Palo Alto Research Center (PARC) in the late 1970 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Business Delegate Pattern
Business delegate is a Java EE design pattern. This pattern is directed towards reducing the coupling in between business services and the connected presentation tier, and to hide the implementation details of services (including lookup and accessibility of EJB architecture). Business delegates acts as an adaptor to invoke business objects from the presentation tier. Structure Requests to access underlying business services are sent from clients, and lookup services are used by business delegates to locate the business service components. Components Basic components are Business delegate, Lookup service and business service. Business delegate Control and protection are provided through business delegate which can have two types of structures, without ID and with ID, where ID is a string version of the reference to a remote object such as EJBHome or EJBObject. Lookup service Business service is located by lookup service which is used by the business delegate. The implementation d ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Inheritance (object-oriented Programming)
In object-oriented programming, inheritance is the mechanism of basing an Object (computer science), object or Class (computer programming), class upon another object (Prototype-based programming, prototype-based inheritance) or class (Class-based programming, class-based inheritance), retaining similar implementation. Also defined as deriving new classes (#Subclasses and superclasses, sub classes) from existing ones such as super class or Fragile base class, base class and then forming them into a hierarchy of classes. In most class-based object-oriented languages like C++, an object created through inheritance, a "child object", acquires all the properties and behaviors of the "parent object", with the exception of: Constructor (object-oriented programming), constructors, destructors, operator overloading, 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 implementat ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mixin
In object-oriented programming languages, a mixin (or mix-in) 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". Mixins encourage code reuse and can be used to avoid the inheritance ambiguity that multiple inheritance can cause (the " diamond problem"), or to work around lack of support for multiple inheritance in a language. A mixin can also be viewed as an interface with implemented methods. This pattern is an example of enforcing the dependency inversion principle. History Mixins first appeared in Symbolics's object-oriented Flavors system (developed by Howard Cannon), which was an approach to object-orientation used in Lisp Machine Lisp. The name was inspired by Steve's Ice Cream Parlor in Somerville, Massachusetts: The owner of the ice cream ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
