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Creational Pattern
In software engineering, creational design patterns are design patterns that deal with object creation mechanisms, trying to create objects in a manner suitable to the situation. The basic form of object creation could result in design problems or in added complexity to the design. Creational design patterns solve this problem by somehow controlling this object creation. Overview Creational design patterns are composed of two dominant ideas. One is encapsulating knowledge about which concrete classes the system uses. Another is hiding how instances of these concrete classes are created and combined. Creational design patterns are further categorized into object-creational patterns and class-creational patterns, where object-creational patterns deal with object creation and class-creational patterns deal with class-instantiation. In greater details, object-creational patterns defer part of its object creation to another object, while class-creational patterns defer its object cre ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Software Engineering
Software engineering is a systematic engineering approach to software development. A software engineer is a person who applies the principles of software engineering to design, develop, maintain, test, and evaluate computer software. The term '' programmer'' is sometimes used as a synonym, but may also lack connotations of engineering education or skills. Engineering techniques are used to inform the software development process which involves the definition, implementation, assessment, measurement, management, change, and improvement of the software life cycle process itself. It heavily uses software configuration management which is about systematically controlling changes to the configuration, and maintaining the integrity and traceability of the configuration and code throughout the system life cycle. Modern processes use software versioning. History Beginning in the 1960s, software engineering was seen as its own type of engineering. Additionally, the development of soft ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Abstract Factory Pattern
The abstract factory pattern provides a way to encapsulate a group of individual factories that have a common theme without specifying their concrete classes. In normal usage, the client software creates a concrete implementation of the abstract factory and then uses the generic interface of the factory to create the concrete objects that are part of the theme. The client does not know (or care) which concrete objects it gets from each of these internal factories, since it uses only the generic interfaces of their products. This pattern separates the details of implementation of a set of objects from their general usage and relies on object composition, as object creation is implemented in methods exposed in the factory interface. An example of this would be an abstract factory class DocumentCreator that provides interfaces to create a number of products (e.g., createLetter() and createResume()). The system would have any number of derived concrete versions of the DocumentCreator cl ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Concurrency Pattern
In software engineering, concurrency patterns are those types of design patterns that deal with the multi-threaded programming paradigm. Examples of this class of patterns include: * Active Object * Balking pattern * Barrier * Double-checked locking * Guarded suspension * Leaders/followers pattern * Monitor Object * Nuclear reaction * Reactor pattern * Read write lock pattern * Scheduler pattern * Thread pool pattern * Thread-local storage See also * Design Patterns *Behavioral pattern *Creational pattern *Structural pattern In software engineering, structural design patterns are design patterns that ease the design by identifying a simple way to realize relationships among entities. Examples of Structural Patterns include: * Adapter pattern: 'adapts' one interface fo ... References External links ScaleConf Presentation about concurrency patternsGopherCon Rethinking Classical Concurrency Patterns [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Behavioral Pattern
In software engineering, behavioral design patterns are design patterns that identify common communication patterns among objects. By doing so, these patterns increase flexibility in carrying out communication. Design patterns Examples of this type of design pattern include: * Blackboard design pattern: provides a computational framework for the design and implementation of systems that integrate large and diverse specialized modules, and implement complex, non-deterministic control strategies * Chain of responsibility pattern: Command objects are handled or passed on to other objects by logic-containing processing objects * Command pattern: Command objects encapsulate an action and its parameters * "Externalize the stack": Turn a recursive function into an iterative one that uses a stack * Interpreter pattern: Implement a specialized computer language to rapidly solve a specific set of problems * Iterator pattern: Iterators are used to access the elements of an aggregate objec ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Constructor (object-oriented Programming)
In class-based, object-oriented programming, a constructor (abbreviation: ctor) is a special type of subroutine called to create an object. It prepares the new object for use, often accepting arguments that the constructor uses to set required member variables. A constructor resembles an instance method, but it differs from a method in that it has no explicit return type, it is not implicitly inherited and it usually has different rules for scope modifiers. Constructors often have the same name as the declaring class. They have the task of initializing the object's data members and of establishing the invariant of the class, failing if the invariant is invalid. A properly written constructor leaves the resulting object in a ''valid'' state. Immutable objects must be initialized in a constructor. Most languages allow overloading the constructor in that there can be more than one constructor for a class, with differing parameters. Some languages take consideration of some sp ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Singleton Pattern
In software engineering, the singleton pattern is a software design pattern that restricts the instantiation of a class to a singular instance. One of the well-known "Gang of Four" design patterns, which describe how to solve recurring problems in object-oriented software, the pattern is useful when exactly one object is needed to coordinate actions across a system. More specifically, the singleton pattern allows objects to: * Ensure they only have one instance * Provide easy access to that instance * Control their instantiation (for example, hiding the constructors of a class) The term comes from the mathematical concept of a singleton. Common uses Singletons are often preferred to global variables because they do not pollute the global namespace (or their containing namespace). Additionally, they permit lazy allocation and initialization, whereas global variables in many languages will always consume resources. The singleton pattern can also be used as a basis for oth ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Prototype Pattern
The prototype pattern is a creational design pattern (computer science), design pattern in software development. It is used when the type of object (computer science), objects to create is determined by a prototype, prototypical instance (computer science), instance, which is cloned to produce new objects. This pattern is used to avoid subclass (computer science), subclasses of an object creator in the client application, like the factory method pattern does and to avoid the inherent cost of creating a new object in the standard way (e.g., using the 'new (C++), new' keyword) when it is prohibitively expensive for a given application. To implement the pattern, the client declares an abstract base class that specifies a virtual method#Abstract classes and pure virtual functions, pure virtual ''clone()'' method. Any class that needs a "polymorphism (computer science), polymorphic constructor (computer science), constructor" capability derives itself from the abstract base class, and ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Object Pool Pattern
The object pool pattern is a software creational design pattern that uses a set of initialized objects kept ready to use – a "pool" – rather than allocating and destroying them on demand. A client of the pool will request an object from the pool and perform operations on the returned object. When the client has finished, it returns the object to the pool rather than destroying it; this can be done manually or automatically. Object pools are primarily used for performance: in some circumstances, object pools significantly improve performance. Object pools complicate object lifetime, as objects obtained from and returned to a pool are not actually created or destroyed at this time, and thus require care in implementation. Description When it is necessary to work with numerous objects that are particularly expensive to instantiate and each object is only needed for a short period of time, the performance of an entire application may be adversely affected. An object pool desig ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lazy Initialization Pattern
In computer programming, lazy initialization is the tactic of delaying the creation of an object, the calculation of a value, or some other expensive process until the first time it is needed. It is a kind of lazy evaluation that refers specifically to the instantiation of objects or other resources. This is typically accomplished by augmenting an accessor method (or property getter) to check whether a private member, acting as a cache, has already been initialized. If it has, it is returned straight away. If not, a new instance is created, placed into the member variable, and returned to the caller just-in-time for its first use. If objects have properties that are rarely used, this can improve startup speed. Mean average program performance may be slightly worse in terms of memory (for the condition variables) and execution cycles (to check them), but the impact of object instantiation is spread in time ("amortized") rather than concentrated in the startup phase of a system, and ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Builder Pattern
The builder pattern is a design pattern designed to provide a flexible solution to various object creation problems in object-oriented programming. The intent of the Builder design pattern is to separate the construction of a complex object from its representation. It is one of the Gang of Four design patterns. Overview The Builder design pattern is one of the ''Design Patterns'' that describe how to solve recurring design problems in object-oriented software. The Builder design pattern solves problems like: * How can a class (the same construction process) create different representations of a complex object? * How can a class that includes creating a complex object be simplified? Creating and assembling the parts of a complex object directly within a class is inflexible. It commits the class to creating a particular representation of the complex object and makes it impossible to change the representation later independently from (without having to change) the class. The Build ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Factory Method Pattern
In class-based programming, the factory method pattern is a creational pattern that uses factory methods to deal with the problem of creating objects without having to specify the exact class of the object that will be created. This is done by creating objects by calling a factory method—either specified in an interface and implemented by child classes, or implemented in a base class and optionally overridden by derived classes—rather than by calling a constructor. Overview The Factory Method design pattern is one of the twenty-three well-known '' design patterns'' that describe how to solve recurring design problems to design flexible and reusable object-oriented software, that is, objects that are easier to implement, change, test, and reuse. The Factory Method design pattern solves problems like: * How can an object be created so that subclasses can redefine which class to instantiate? * How can a class defer instantiation to subclasses? The Factory Method design patt ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
