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In object-oriented programming, the template method is one of the behavioral design patterns identified by Gamma et al. [1] in the book Design Patterns.The template method is a method in a superclass, usually an abstract superclass, and defines the skeleton of an operation in terms of a number of high-level steps.
Template method: Define the skeleton of an algorithm in an operation, deferring some steps to subclasses. Template method lets subclasses redefine certain steps of an algorithm without changing the algorithm's structure. Yes Yes Yes Visitor: Represent an operation to be performed on instances of a set of classes.
The visitor pattern may be used for iteration over container-like data structures just like Iterator pattern but with limited functionality. [3]: 288 For example, iteration over a directory structure could be implemented by a function class instead of more conventional loop 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.
The authors employ the term 'toolkit' where others might today use 'class library', as in C# or Java. In their parlance, toolkits are the object-oriented equivalent of subroutine libraries, whereas a ' framework ' is a set of cooperating classes that make up a reusable design for a specific class of software.
A sample UML class and sequence diagram for the Iterator design pattern. [4] In the above UML class diagram, the Client class refers (1) to the Aggregate interface for creating an Iterator object (createIterator()) and (2) to the Iterator interface for traversing an Aggregate object (next(),hasNext()).
Whereas the singleton allows only one instance of a class to be created, the multiton pattern allows for the controlled creation of multiple instances, which it manages through the use of a map. Rather than having a single instance per application (e.g. the java.lang.Runtime object in the Java programming language ) the multiton pattern instead ...
The bridge pattern is useful when both the class and what it does vary often. The class itself can be thought of as the abstraction and what the class can do as the implementation. The bridge pattern can also be thought of as two layers of abstraction. When there is only one fixed implementation, this pattern is known as the Pimpl idiom in the ...