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The observer design pattern is a behavioural pattern listed among the 23 well-known "Gang of Four" design patterns that address recurring design challenges in order to design flexible and reusable object-oriented software, yielding objects that are easier to implement, change, test and reuse. [1]
The Listener Pattern is typically known as Observer Pattern. It is a Behavioral Pattern (aka Publish-Subscribe ), which deals with dynamic changes in the state of different objects. Listener Pattern follows a structure where an event listener is registered to event source .
Signals and slots is a language construct introduced in Qt [1] for communication between objects which makes it easy to implement the observer pattern while avoiding boilerplate code. The concept is that GUI widgets , and other objects, can send signals containing event information which can be received by other objects using special member ...
Memento pattern Provides the ability to restore an object to its previous state (rollback) Null object pattern Designed to act as a default value of an object Observer pattern a.k.a. Publish/Subscribe or Event Listener. Objects register to observe an event that may be raised by another object Weak reference pattern De-couple an observer from an ...
Design Patterns: Elements of Reusable Object-Oriented Software (1994) is a software engineering book describing software design patterns. The book was written by Erich Gamma , Richard Helm , Ralph Johnson , and John Vlissides , with a foreword by Grady Booch .
A design pattern is the re-usable form of a solution to a design problem. The idea was introduced by the architect Christopher Alexander [ 1 ] and has been adapted for various other disciplines, particularly software engineering .
In object-oriented programming, the iterator pattern is a design pattern in which an iterator is used to traverse a container and access the container's elements. The iterator pattern decouples algorithms from containers; in some cases, algorithms are necessarily container-specific and thus cannot be decoupled.
The state pattern is a behavioral software design pattern that allows an object to alter its behavior when its internal state changes. This pattern is close to the concept of finite-state machines . The state pattern can be interpreted as a strategy pattern , which is able to switch a strategy through invocations of methods defined in the ...