Basic knowledge of the Design Pattern.
A software design pattern is a general, reusable solution to a commonly occurring problem within a given context in software design. It is not a finished design that can be transformed directly into source or machine code. It is a description or template for how to solve a problem that can be used in many different situations. Design patterns are formalized best practices that the programmer can use to solve common problems when designing an application or system.
Object-oriente 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 not necessarily suitable for non-object-oriented languages.
Design patterns may be viewed as a structured approach to computer programming intermediate between the levels of a programming paradigm and a concrete algorithm.
These are types of design patterns .
Creational patterns[edit]
Name
|
Description
|
Other
|
||
Provide an interface for creating families of
related or dependent objects without specifying their concrete classes.
|
Yes
|
Yes
|
N/A
|
|
Separate the construction of a complex object from its
representation, allowing the same construction process to create various
representations.
|
Yes
|
No
|
N/A
|
|
A class accepts the objects it requires from an injector
instead of creating the objects directly.
|
No
|
No
|
N/A
|
|
Define an interface for creating a single object,
but let subclasses decide which class to instantiate. Factory Method lets a
class defer instantiation to subclasses.
|
Yes
|
Yes
|
N/A
|
|
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. This pattern appears in the GoF catalog as "virtual
proxy", an implementation strategy for the Proxy pattern.
|
Yes
|
No
|
PoEAA[14]
|
|
Ensure a class has only named instances, and provide a
global point of access to them.
|
No
|
No
|
N/A
|
|
Avoid expensive acquisition and release of resources by
recycling objects that are no longer in use. Can be considered a
generalisation of connection pool and thread
pool patterns.
|
No
|
No
|
N/A
|
|
Specify the kinds of objects to create using a
prototypical instance, and create new objects from the 'skeleton' of an
existing object, thus boosting performance and keeping memory footprints to a
minimum.
|
Yes
|
No
|
N/A
|
|
Ensure that resources are properly released by tying them
to the lifespan of suitable objects.
|
No
|
No
|
N/A
|
|
Ensure a class has only one instance, and provide a global
point of access to it.
|
Yes
|
Yes
|
N/A
|
Name
|
Description
|
Other
|
||
Adapter, Wrapper, or Translator
|
Convert the interface of a class into another interface
clients expect. An adapter lets classes work together that could not
otherwise because of incompatible interfaces. The enterprise integration
pattern equivalent is the translator.
|
Yes
|
Yes
|
N/A
|
Decouple an abstraction from its implementation allowing
the two to vary independently.
|
Yes
|
Yes
|
N/A
|
|
Compose objects into tree structures to represent
part-whole hierarchies. Composite lets clients treat individual objects and
compositions of objects uniformly.
|
Yes
|
Yes
|
N/A
|
|
Attach additional responsibilities to an object
dynamically keeping the same interface. Decorators provide a flexible
alternative to subclassing for extending functionality.
|
Yes
|
Yes
|
N/A
|
|
Extension object
|
Adding functionality to a hierarchy without changing the
hierarchy.
|
No
|
No
|
Agile Software Development, Principles, Patterns, and
Practices[15]
|
Provide a unified interface to a set of interfaces in a
subsystem. Facade defines a higher-level interface that makes the subsystem
easier to use.
|
Yes
|
Yes
|
N/A
|
|
Use sharing to support large numbers of similar objects
efficiently.
|
Yes
|
No
|
N/A
|
|
The pattern relates to the design of Web applications. It
provides a centralized entry point for handling requests.
|
No
|
No
|
||
Empty interface to associate metadata with a class.
|
No
|
No
|
||
Group several related elements, such as classes,
singletons, methods, globally used, into a single conceptual entity.
|
No
|
No
|
N/A
|
|
Provide a surrogate or placeholder for another object to
control access to it.
|
Yes
|
No
|
N/A
|
|
Twin allows modeling of multiple inheritance in
programming languages that do not support this feature.
|
No
|
No
|
N/A
|
Name
|
Description
|
Other
|
||
No
|
No
|
N/A
|
||
Avoid coupling the sender of a request to its receiver by
giving more than one object a chance to handle the request. Chain the
receiving objects and pass the request along the chain until an object
handles it.
|
Yes
|
No
|
N/A
|
|
Encapsulate a request as an object, thereby allowing for
the parameterization of clients with different requests, and the queuing or
logging of requests. It also allows for the support of undoable operations.
|
Yes
|
No
|
N/A
|
|
Given a language, define a representation for its grammar
along with an interpreter that uses the representation to interpret sentences
in the language.
|
Yes
|
No
|
N/A
|
|
Provide a way to access the elements of an aggregate object sequentially without
exposing its underlying representation.
|
Yes
|
Yes
|
N/A
|
|
Define an object that encapsulates how a set of objects
interact. Mediator promotes loose
coupling by keeping objects from referring to each other explicitly,
and it allows their interaction to vary independently.
|
Yes
|
No
|
N/A
|
|
Without violating encapsulation, capture and externalize
an object's internal state allowing the object to be restored to this state
later.
|
Yes
|
No
|
N/A
|
|
Avoid null references by providing a default object.
|
No
|
No
|
N/A
|
|
Define a one-to-many dependency between objects where a
state change in one object results in all its dependents being notified and
updated automatically.
|
Yes
|
Yes
|
N/A
|
|
Define common functionality for a group of classes.
|
No
|
No
|
N/A
|
|
No
|
No
|
N/A
|
||
Allow an object to alter its behavior when its internal
state changes. The object will appear to change its class.
|
Yes
|
No
|
N/A
|
|
Define a family of algorithms, encapsulate each one, and
make them interchangeable. Strategy lets the algorithm vary independently
from clients that use it.
|
Yes
|
Yes
|
N/A
|
|
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
|
N/A
|
|
Represent an operation to be performed on the elements of
an object structure. Visitor lets a new operation be defined without changing
the classes of the elements on which it operates.
|
Yes
|
No
|
N/A
|
Name
|
Description
|
Other
|
|
Decouples method execution from method invocation that
reside in their own thread of control. The goal is to introduce concurrency,
by using asynchronous method invocation and
a scheduler for handling requests.
|
Yes
|
N/A
|
|
Only execute an action on an object when the object is in
a particular state.
|
No
|
N/A
|
|
Combining multiple observers to force properties in
different objects to be synchronized or coordinated in some way.[21]
|
No
|
N/A
|
|
The same calculation many times in parallel, differing by
integer parameters used with non-branching pointer math into shared arrays,
such as GPU-optimized Matrix multiplication or Convolutional neural network.
|
No
|
N/A
|
|
Reduce the overhead of acquiring a lock by first testing
the locking criterion (the 'lock hint') in an unsafe manner; only if that
succeeds does the actual locking logic proceed.
Can be unsafe when implemented in some language/hardware
combinations. It can therefore sometimes be considered an anti-pattern.
|
Yes
|
N/A
|
|
Addresses problems with the asynchronous pattern that
occur in multithreaded programs.[22]
|
No
|
N/A
|
|
Manages operations that require both a lock to be acquired
and a precondition to be satisfied before the operation can be executed.
|
No
|
N/A
|
|
Join-pattern provides a way to write concurrent, parallel
and distributed programs by message passing. Compared to the use of threads
and locks, this is a high-level programming model.
|
No
|
N/A
|
|
One thread puts a "lock" on a resource,
preventing other threads from accessing or modifying it.[23]
|
No
|
PoEAA[14]
|
|
Allows the interchange of information (i.e. messages)
between components and applications.
|
No
|
N/A
|
|
An object whose methods are subject to mutual
exclusion, thus preventing multiple objects from erroneously trying to
use it at the same time.
|
Yes
|
N/A
|
|
A reactor object provides an asynchronous interface to
resources that must be handled synchronously.
|
Yes
|
N/A
|
|
Allows concurrent read access to an object, but requires
exclusive access for write operations.
|
No
|
N/A
|
|
Explicitly control when threads may execute
single-threaded code.
|
No
|
N/A
|
|
A number of threads are created to perform a number of
tasks, which are usually organized in a queue. Typically, there are many more
tasks than threads. Can be considered a special case of the object
pool pattern.
|
No
|
N/A
|
|
Static or "global" memory local to a thread.
|
Yes
|
N/A
|
Basic knowledge of the Design Pattern.
Reviewed by Mukesh Jha
on
11:25 PM
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