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Creational Patterns
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 due to inflexibility in the creation procedures. 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, whi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Software Engineering
Software engineering is a branch of both computer science and engineering focused on designing, developing, testing, and maintaining Application software, software applications. It involves applying engineering design process, engineering principles and computer programming expertise to develop software systems that meet user needs. The terms ''programmer'' and ''coder'' overlap ''software engineer'', but they imply only the construction aspect of a typical software engineer workload. A software engineer applies a software development process, which involves defining, Implementation, implementing, Software testing, testing, Project management, managing, and Software maintenance, maintaining software systems, as well as developing the software development process itself. History Beginning in the 1960s, software engineering was recognized as a separate field of engineering. The development of software engineering was seen as a struggle. Problems included software that was over ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Abstract Factory Pattern
The abstract factory pattern in software engineering is a design pattern that provides a way to create families of related objects without imposing their concrete classes, by encapsulating a group of individual factories that have a common theme without specifying their concrete classes. According to this pattern, a client software component 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 family. The client does not know which concrete objects it receives from each of these internal factories, as 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. Use of this pattern enables interchangeable concrete implementations without changing the code that uses them, ev ... [...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 * Readers–writer lock * Scheduler pattern * Thread pool pattern * Thread-local storage See also * '' Design Patterns'' (book) * Behavioral pattern * Creational pattern In software engineering, creational design patterns are design patterns that deal with object creation Object may refer to: General meanings * Object (philosophy), a thing, being, or concept ** Object (abstract), an object which does not ex ... * Structural pattern 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 function 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 aggreg ... [...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 function 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 object-oriented programming, the singleton pattern is a software design pattern that restricts the instantiation of a class to a singular instance. It is 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 classes 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 ... [...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 types 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, a ... [...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 desi ... [...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, an ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dependency Injection
In software engineering, dependency injection is a programming technique in which an object or function receives other objects or functions that it requires, as opposed to creating them internally. Dependency injection aims to separate the concerns of constructing objects and using them, leading to loosely coupled programs. The pattern ensures that an object or function that wants to use a given service should not have to know how to construct those services. Instead, the receiving " client" (object or function) is provided with its dependencies by external code (an "injector"), which it is not aware of. Dependency injection makes implicit dependencies explicit and helps solve the following problems: * How can a class be independent from the creation of the objects it depends on? * How can an application, and the objects it uses support different configurations? Dependency injection is often used to keep code in-line with the dependency inversion principle. In statically ty ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Builder Pattern
The builder pattern is a design pattern that provides a flexible solution to various object creation problems in object-oriented programming. The builder pattern separates the construction of a complex object from its representation. It is one of the 23 classic design patterns described in the book ''Design Patterns'' and is sub-categorized as a creational pattern. Overview 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 builder design pattern describes how to solve such problems: * Encapsulate creating and assemb ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Factory Method Pattern
In object-oriented programming, the factory method pattern is a software design pattern, design pattern that uses factory methods to deal with the problem of object creation, creating objects without having to specify their exact class (computer programming), classes. Rather than by calling a Constructor (object-oriented programming), constructor, this is accomplished by invoking a factory method to create an object. Factory methods can be specified in an Interface (object-oriented programming), interface and implemented by subclasses or implemented in a base class and optionally method overriding, overridden by subclasses. It is one of the 23 classic design patterns described in the book ''Design Patterns'' (often referred to as the "Gang of Four" or simply "GoF") and is subcategorized as a creational pattern. Overview The factory method design pattern solves problems such as: * How can an object's Subclass (computer science), subclasses redefine its subsequent and distinct impleme ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
