Work towards : Add permalink to every pattern

This makes cleaner URLs thanks to jekyll
This commit is contained in:
Markus 2015-08-15 18:03:05 +02:00
parent fbb12b53ba
commit fdb9be1e76
57 changed files with 113 additions and 80 deletions
abstract-factory
adapter
async-method-invocation
bridge
builder
business-delegate
callback
chain-of-responsibility
command
composite
dao
decorator
dependency-injection
double-checked-locking
double-dispatch
event-aggregator
execute-around
facade
factory-method
flux
flyweight
front-controller
half-sync-half-async
idioms
intercepting-filter
interpreter
introduction
iterator
lazy-loading
mediator
memento
model-view-controller
model-view-presenter
multiton
naked-objects
null-object
object-pool
observer
poison-pill
private-class-data
property
prototype
proxy
repository
resource-acquisition-is-initialization
servant
service-layer
service-locator
singleton
specification
state
step-builder
strategy
template-method
thread-pool
tolerant-reader
visitor

@ -2,6 +2,7 @@
layout: pattern layout: pattern
title: Abstract Factory title: Abstract Factory
folder: abstract-factory folder: abstract-factory
permalink: /patterns/abstract-factory/
categories: categories:
- pattern_cat - pattern_cat
- creational - creational
@ -22,4 +23,4 @@ objects without specifying their concrete classes.
**Real world examples:** **Real world examples:**
* [javax.xml.parsers.DocumentBuilderFactory](http://docs.oracle.com/javase/8/docs/api/javax/xml/parsers/DocumentBuilderFactory.html) * [javax.xml.parsers.DocumentBuilderFactory](http://docs.oracle.com/javase/8/docs/api/javax/xml/parsers/DocumentBuilderFactory.html)

@ -2,6 +2,7 @@
layout: pattern layout: pattern
title: Adapter title: Adapter
folder: adapter folder: adapter
permalink: /patterns/adapter/
categories: pattern_cat categories: pattern_cat
tags: pattern_tag tags: pattern_tag
--- ---
@ -20,4 +21,4 @@ incompatible interfaces.
**Real world examples:** **Real world examples:**
* [java.util.Arrays#asList()](http://docs.oracle.com/javase/8/docs/api/java/util/Arrays.html#asList%28T...%29) * [java.util.Arrays#asList()](http://docs.oracle.com/javase/8/docs/api/java/util/Arrays.html#asList%28T...%29)

@ -2,6 +2,7 @@
layout: pattern layout: pattern
title: Async Method Invocation title: Async Method Invocation
folder: async-method-invocation folder: async-method-invocation
permalink: /patterns/async-method-invocation/
categories: pattern_cat categories: pattern_cat
tags: pattern_tag tags: pattern_tag
--- ---
@ -23,4 +24,4 @@ callbacks or waiting until everything is done.
**Real world examples:** **Real world examples:**
* [FutureTask](http://docs.oracle.com/javase/8/docs/api/java/util/concurrent/FutureTask.html), [CompletableFuture](https://docs.oracle.com/javase/8/docs/api/java/util/concurrent/CompletableFuture.html) and [ExecutorService](http://docs.oracle.com/javase/8/docs/api/java/util/concurrent/ExecutorService.html) (Java) * [FutureTask](http://docs.oracle.com/javase/8/docs/api/java/util/concurrent/FutureTask.html), [CompletableFuture](https://docs.oracle.com/javase/8/docs/api/java/util/concurrent/CompletableFuture.html) and [ExecutorService](http://docs.oracle.com/javase/8/docs/api/java/util/concurrent/ExecutorService.html) (Java)
* [Task-based Asynchronous Pattern](https://msdn.microsoft.com/en-us/library/hh873175.aspx) (.NET) * [Task-based Asynchronous Pattern](https://msdn.microsoft.com/en-us/library/hh873175.aspx) (.NET)

@ -2,6 +2,7 @@
layout: pattern layout: pattern
title: Bridge title: Bridge
folder: bridge folder: bridge
permalink: /patterns/bridge/
categories: pattern_cat categories: pattern_cat
tags: pattern_tag tags: pattern_tag
--- ---
@ -18,4 +19,4 @@ vary independently.
* both the abstractions and their implementations should be extensible by subclassing. In this case, the Bridge pattern lets you combine the different abstractions and implementations and extend them independently * both the abstractions and their implementations should be extensible by subclassing. In this case, the Bridge pattern lets you combine the different abstractions and implementations and extend them independently
* changes in the implementation of an abstraction should have no impact on clients; that is, their code should not have to be recompiled. * changes in the implementation of an abstraction should have no impact on clients; that is, their code should not have to be recompiled.
* you have a proliferation of classes. Such a class hierarchy indicates the need for splitting an object into two parts. Rumbaugh uses the term "nested generalizations" to refer to such class hierarchies * you have a proliferation of classes. Such a class hierarchy indicates the need for splitting an object into two parts. Rumbaugh uses the term "nested generalizations" to refer to such class hierarchies
* you want to share an implementation among multiple objects (perhaps using reference counting), and this fact should be hidden from the client. A simple example is Coplien's String class, in which multiple objects can share the same string representation. * you want to share an implementation among multiple objects (perhaps using reference counting), and this fact should be hidden from the client. A simple example is Coplien's String class, in which multiple objects can share the same string representation.

@ -2,6 +2,7 @@
layout: pattern layout: pattern
title: Builder title: Builder
folder: builder folder: builder
permalink: /patterns/builder/
categories: creational categories: creational
tags: pattern_tag tags: pattern_tag
--- ---
@ -20,4 +21,4 @@ representations.
**Real world examples:** **Real world examples:**
* [java.lang.StringBuilder](http://docs.oracle.com/javase/8/docs/api/java/lang/StringBuilder.html) * [java.lang.StringBuilder](http://docs.oracle.com/javase/8/docs/api/java/lang/StringBuilder.html)
* [Apache Camel builders](https://github.com/apache/camel/tree/0e195428ee04531be27a0b659005e3aa8d159d23/camel-core/src/main/java/org/apache/camel/builder) * [Apache Camel builders](https://github.com/apache/camel/tree/0e195428ee04531be27a0b659005e3aa8d159d23/camel-core/src/main/java/org/apache/camel/builder)

@ -2,6 +2,7 @@
layout: pattern layout: pattern
title: Business Delegate title: Business Delegate
folder: business-delegate folder: business-delegate
permalink: /patterns/business-delegate/
categories: pattern_cat categories: pattern_cat
tags: pattern_tag tags: pattern_tag
--- ---
@ -17,4 +18,4 @@ and interact with the business objects that make up the application.
* you want loose coupling between presentation and business tiers * you want loose coupling between presentation and business tiers
* you want to orchestrate calls to multiple business services * you want to orchestrate calls to multiple business services
* you want to encapsulate service lookups and service calls * you want to encapsulate service lookups and service calls

@ -2,6 +2,7 @@
layout: pattern layout: pattern
title: Callback title: Callback
folder: callback folder: callback
permalink: /patterns/callback/
categories: pattern_cat categories: pattern_cat
tags: pattern_tag tags: pattern_tag
--- ---
@ -18,4 +19,4 @@ at some convenient time.
**Real world examples:** **Real world examples:**
* [CyclicBarrier] (http://docs.oracle.com/javase/7/docs/api/java/util/concurrent/CyclicBarrier.html#CyclicBarrier%28int,%20java.lang.Runnable%29) constructor can accept callback that will be triggered every time when barrier is tripped. * [CyclicBarrier] (http://docs.oracle.com/javase/7/docs/api/java/util/concurrent/CyclicBarrier.html#CyclicBarrier%28int,%20java.lang.Runnable%29) constructor can accept callback that will be triggered every time when barrier is tripped.

@ -2,6 +2,7 @@
layout: pattern layout: pattern
title: Chain of responsibility title: Chain of responsibility
folder: chain-of-responsibility folder: chain-of-responsibility
permalink: /patterns/chain-of-responsibility/
categories: pattern_cat categories: pattern_cat
tags: pattern_tag tags: pattern_tag
--- ---
@ -21,4 +22,4 @@ objects and pass the request along the chain until an object handles it.
**Real world examples:** **Real world examples:**
* [java.util.logging.Logger#log()](http://docs.oracle.com/javase/8/docs/api/java/util/logging/Logger.html#log%28java.util.logging.Level,%20java.lang.String%29) * [java.util.logging.Logger#log()](http://docs.oracle.com/javase/8/docs/api/java/util/logging/Logger.html#log%28java.util.logging.Level,%20java.lang.String%29)
* [Apache Commons Chain](https://commons.apache.org/proper/commons-chain/index.html) * [Apache Commons Chain](https://commons.apache.org/proper/commons-chain/index.html)

@ -2,6 +2,7 @@
layout: pattern layout: pattern
title: Command title: Command
folder: command folder: command
permalink: /patterns/command/
categories: pattern_cat categories: pattern_cat
tags: pattern_tag tags: pattern_tag
--- ---
@ -28,4 +29,4 @@ support undoable operations.
**Real world examples:** **Real world examples:**
* [java.lang.Runnable](http://docs.oracle.com/javase/8/docs/api/java/lang/Runnable.html) * [java.lang.Runnable](http://docs.oracle.com/javase/8/docs/api/java/lang/Runnable.html)

@ -2,6 +2,7 @@
layout: pattern layout: pattern
title: Composite title: Composite
folder: composite folder: composite
permalink: /patterns/composite/
categories: pattern_cat categories: pattern_cat
tags: pattern_tag tags: pattern_tag
--- ---
@ -20,4 +21,4 @@ of objects uniformly.
**Real world examples:** **Real world examples:**
* [java.awt.Container](http://docs.oracle.com/javase/8/docs/api/java/awt/Container.html) and [java.awt.Component](http://docs.oracle.com/javase/8/docs/api/java/awt/Component.html) * [java.awt.Container](http://docs.oracle.com/javase/8/docs/api/java/awt/Container.html) and [java.awt.Component](http://docs.oracle.com/javase/8/docs/api/java/awt/Component.html)
* [Apache Wicket](https://github.com/apache/wicket) component tree, see [Component](https://github.com/apache/wicket/blob/91e154702ab1ff3481ef6cbb04c6044814b7e130/wicket-core/src/main/java/org/apache/wicket/Component.java) and [MarkupContainer](https://github.com/apache/wicket/blob/b60ec64d0b50a611a9549809c9ab216f0ffa3ae3/wicket-core/src/main/java/org/apache/wicket/MarkupContainer.java) * [Apache Wicket](https://github.com/apache/wicket) component tree, see [Component](https://github.com/apache/wicket/blob/91e154702ab1ff3481ef6cbb04c6044814b7e130/wicket-core/src/main/java/org/apache/wicket/Component.java) and [MarkupContainer](https://github.com/apache/wicket/blob/b60ec64d0b50a611a9549809c9ab216f0ffa3ae3/wicket-core/src/main/java/org/apache/wicket/MarkupContainer.java)

@ -2,6 +2,7 @@
layout: pattern layout: pattern
title: Data Access Object title: Data Access Object
folder: dao folder: dao
permalink: /patterns/dao/
categories: pattern_cat categories: pattern_cat
tags: pattern_tag tags: pattern_tag
--- ---
@ -14,4 +15,4 @@ other persistence mechanism.
**Applicability:** Use the Data Access Object in any of the following situations **Applicability:** Use the Data Access Object in any of the following situations
* when you want to consolidate how the data layer is accessed * when you want to consolidate how the data layer is accessed
* when you want to avoid writing multiple data retrieval/persistence layers * when you want to avoid writing multiple data retrieval/persistence layers

@ -2,6 +2,7 @@
layout: pattern layout: pattern
title: Decorator title: Decorator
folder: decorator folder: decorator
permalink: /patterns/decorator/
categories: pattern_cat categories: pattern_cat
tags: pattern_tag tags: pattern_tag
--- ---
@ -16,4 +17,4 @@ functionality.
* to add responsibilities to individual objects dynamically and transparently, that is, without affecting other objects * to add responsibilities to individual objects dynamically and transparently, that is, without affecting other objects
* for responsibilities that can be withdrawn * for responsibilities that can be withdrawn
* when extension by subclassing is impractical. Sometimes a large number of independent extensions are possible and would produce an explosion of subclasses to support every combination. Or a class definition may be hidden or otherwise unavailable for subclassing * when extension by subclassing is impractical. Sometimes a large number of independent extensions are possible and would produce an explosion of subclasses to support every combination. Or a class definition may be hidden or otherwise unavailable for subclassing

@ -2,6 +2,7 @@
layout: pattern layout: pattern
title: Dependency Injection title: Dependency Injection
folder: dependency-injection folder: dependency-injection
permalink: /patterns/dependency-injection/
categories: pattern_cat categories: pattern_cat
tags: pattern_tag tags: pattern_tag
--- ---
@ -18,4 +19,4 @@ inversion of control and single responsibility principles.
**Applicability:** Use the Dependency Injection pattern when **Applicability:** Use the Dependency Injection pattern when
* when you need to remove knowledge of concrete implementation from object * when you need to remove knowledge of concrete implementation from object
* to enable unit testing of classes in isolation using mock objects or stubs * to enable unit testing of classes in isolation using mock objects or stubs

@ -2,6 +2,7 @@
layout: pattern layout: pattern
title: Double Checked Locking title: Double Checked Locking
folder: double-checked-locking folder: double-checked-locking
permalink: /patterns/double-checked-locking/
categories: pattern_cat categories: pattern_cat
tags: pattern_tag tags: pattern_tag
--- ---
@ -16,4 +17,4 @@ actual locking logic proceed.
**Applicability:** Use the Double Checked Locking pattern when **Applicability:** Use the Double Checked Locking pattern when
* there is a concurrent access in object creation, e.g. singleton, where you want to create single instance of the same class and checking if it's null or not maybe not be enough when there are two or more threads that checks if instance is null or not. * there is a concurrent access in object creation, e.g. singleton, where you want to create single instance of the same class and checking if it's null or not maybe not be enough when there are two or more threads that checks if instance is null or not.
* there is a concurrent access on a method where method's behaviour changes according to the some constraints and these constraint change within this method. * there is a concurrent access on a method where method's behaviour changes according to the some constraints and these constraint change within this method.

@ -2,6 +2,7 @@
layout: pattern layout: pattern
title: Double Dispatch title: Double Dispatch
folder: double-dispatch folder: double-dispatch
permalink: /patterns/double-dispatch/
categories: pattern_cat categories: pattern_cat
tags: pattern_tag tags: pattern_tag
--- ---
@ -17,4 +18,4 @@ behavior based on receiver and parameter types.
**Real world examples:** **Real world examples:**
* [ObjectOutputStream](https://docs.oracle.com/javase/8/docs/api/java/io/ObjectOutputStream.html) * [ObjectOutputStream](https://docs.oracle.com/javase/8/docs/api/java/io/ObjectOutputStream.html)

@ -2,6 +2,7 @@
layout: pattern layout: pattern
title: Event Aggregator title: Event Aggregator
folder: event-aggregator folder: event-aggregator
permalink: /patterns/event-aggregator/
categories: pattern_cat categories: pattern_cat
tags: pattern_tag tags: pattern_tag
--- ---
@ -21,4 +22,4 @@ allowing clients to register with just the aggregator.
potential event sources. Rather than have the observer deal with registering potential event sources. Rather than have the observer deal with registering
with them all, you can centralize the registration logic to the Event with them all, you can centralize the registration logic to the Event
Aggregator. As well as simplifying registration, a Event Aggregator also Aggregator. As well as simplifying registration, a Event Aggregator also
simplifies the memory management issues in using observers. simplifies the memory management issues in using observers.

@ -2,6 +2,7 @@
layout: pattern layout: pattern
title: Execute Around title: Execute Around
folder: execute-around folder: execute-around
permalink: /patterns/execute-around/
categories: pattern_cat categories: pattern_cat
tags: pattern_tag tags: pattern_tag
--- ---
@ -15,4 +16,4 @@ only what to do with the resource.
**Applicability:** Use the Execute Around idiom when **Applicability:** Use the Execute Around idiom when
* you use an API that requires methods to be called in pairs such as open/close or allocate/deallocate. * you use an API that requires methods to be called in pairs such as open/close or allocate/deallocate.

@ -2,6 +2,7 @@
layout: pattern layout: pattern
title: Facade title: Facade
folder: facade folder: facade
permalink: /patterns/facade/
categories: pattern_cat categories: pattern_cat
tags: pattern_tag tags: pattern_tag
--- ---
@ -15,4 +16,4 @@ Facade defines a higher-level interface that makes the subsystem easier to use.
* you want to provide a simple interface to a complex subsystem. Subsystems often get more complex as they evolve. Most patterns, when applied, result in more and smaller classes. This makes the subsystem more reusable and easier to customize, but it also becomes harder to use for clients that don't need to customize it. A facade can provide a simple default view of the subsystem that is good enough for most clients. Only clients needing more customizability will need to look beyond the facade. * you want to provide a simple interface to a complex subsystem. Subsystems often get more complex as they evolve. Most patterns, when applied, result in more and smaller classes. This makes the subsystem more reusable and easier to customize, but it also becomes harder to use for clients that don't need to customize it. A facade can provide a simple default view of the subsystem that is good enough for most clients. Only clients needing more customizability will need to look beyond the facade.
* there are many dependencies between clients and the implementation classes of an abstraction. Introduce a facade to decouple the subsystem from clients and other subsystems, thereby promoting subsystem independence and portability. * there are many dependencies between clients and the implementation classes of an abstraction. Introduce a facade to decouple the subsystem from clients and other subsystems, thereby promoting subsystem independence and portability.
* you want to layer your subsystems. Use a facade to define an entry point to each subsystem level. If subsystems are dependent, the you can simplify the dependencies between them by making them communicate with each other solely through their facades * you want to layer your subsystems. Use a facade to define an entry point to each subsystem level. If subsystems are dependent, the you can simplify the dependencies between them by making them communicate with each other solely through their facades

@ -2,6 +2,7 @@
layout: pattern layout: pattern
title: Factory Method title: Factory Method
folder: factory-method folder: factory-method
permalink: /patterns/factory-method/
categories: creational categories: creational
tags: pattern_tag tags: pattern_tag
--- ---
@ -16,4 +17,4 @@ instantiation to subclasses.
* a class can't anticipate the class of objects it must create * a class can't anticipate the class of objects it must create
* a class wants its subclasses to specify the objects it creates * a class wants its subclasses to specify the objects it creates
* classes delegate responsibility to one of several helper subclasses, and you want to localize the knowledge of which helper subclass is the delegate * classes delegate responsibility to one of several helper subclasses, and you want to localize the knowledge of which helper subclass is the delegate

@ -2,6 +2,7 @@
layout: pattern layout: pattern
title: Flux title: Flux
folder: flux folder: flux
permalink: /patterns/flux/
categories: pattern_cat categories: pattern_cat
tags: pattern_tag tags: pattern_tag
--- ---
@ -15,4 +16,4 @@ logic, which updates all of the views that are affected.
**Applicability:** Use the Flux pattern when **Applicability:** Use the Flux pattern when
* you want to focus on creating explicit and understandable update paths for your application's data, which makes tracing changes during development simpler and makes bugs easier to track down and fix. * you want to focus on creating explicit and understandable update paths for your application's data, which makes tracing changes during development simpler and makes bugs easier to track down and fix.

@ -2,6 +2,7 @@
layout: pattern layout: pattern
title: Flyweight title: Flyweight
folder: flyweight folder: flyweight
permalink: /patterns/flyweight/
categories: pattern_cat categories: pattern_cat
tags: pattern_tag tags: pattern_tag
--- ---
@ -22,4 +23,4 @@ true
**Real world examples:** **Real world examples:**
* [java.lang.Integer#valueOf(int)](http://docs.oracle.com/javase/8/docs/api/java/lang/Integer.html#valueOf%28int%29) * [java.lang.Integer#valueOf(int)](http://docs.oracle.com/javase/8/docs/api/java/lang/Integer.html#valueOf%28int%29)

@ -2,6 +2,7 @@
layout: pattern layout: pattern
title: Front Controller title: Front Controller
folder: front-controller folder: front-controller
permalink: /patterns/front-controller/
categories: pattern_cat categories: pattern_cat
tags: pattern_tag tags: pattern_tag
--- ---
@ -20,4 +21,4 @@ internationalization, routing and logging in a single place.
**Real world examples:** **Real world examples:**
* [Apache Struts](https://struts.apache.org/) * [Apache Struts](https://struts.apache.org/)

@ -2,6 +2,7 @@
layout: pattern layout: pattern
title: Half-Sync/Half-Async title: Half-Sync/Half-Async
folder: half-sync-half-async folder: half-sync-half-async
permalink: /patterns/half-sync-half-async/
categories: pattern_cat categories: pattern_cat
tags: pattern_tag tags: pattern_tag
--- ---
@ -24,4 +25,4 @@ degrading execution efficiency.
* [BSD Unix networking subsystem](http://www.cs.wustl.edu/~schmidt/PDF/PLoP-95.pdf) * [BSD Unix networking subsystem](http://www.cs.wustl.edu/~schmidt/PDF/PLoP-95.pdf)
* [Real Time CORBA](http://www.omg.org/news/meetings/workshops/presentations/realtime2001/4-3_Pyarali_thread-pool.pdf) * [Real Time CORBA](http://www.omg.org/news/meetings/workshops/presentations/realtime2001/4-3_Pyarali_thread-pool.pdf)
* [Android AsyncTask framework](http://developer.android.com/reference/android/os/AsyncTask.html) * [Android AsyncTask framework](http://developer.android.com/reference/android/os/AsyncTask.html)

@ -1,24 +0,0 @@
---
layout: pattern
title: Idioms
folder: idioms
categories: pattern_cat
tags: pattern_tag
---
A programming idiom is a means of expressing a recurring construct in one or
more programming languages. Generally speaking, a programming idiom is an
expression of a simple task, algorithm, or data structure that is not a built-in
feature in the programming language being used, or, conversely, the use of an
unusual or notable feature that is built into a programming language. What
distinguishes idioms from patterns is generally the size, the idioms tend to be
something small while the patterns are larger.
* [Execute Around](#execute-around)
* [Poison Pill](#poison-pill)
* [Callback](#callback)
* [Lazy Loading](#lazy-loading)
* [Double Dispatch](#double-dispatch)
* [Resource Acquisition Is Initialization](#resource-acquisition-is-initialization)
* [Private Class Data](#private-class-data)

@ -2,6 +2,7 @@
layout: pattern layout: pattern
title: Intercepting Filter title: Intercepting Filter
folder: intercepting-filter folder: intercepting-filter
permalink: /patterns/intercepting-filter/
categories: pattern_cat categories: pattern_cat
tags: pattern_tag tags: pattern_tag
--- ---
@ -15,4 +16,4 @@ post-processing to requests from a client to a target
* a system uses pre-processing or post-processing requests * a system uses pre-processing or post-processing requests
* a system should do the authentication/ authorization/ logging or tracking of request and then pass the requests to corresponding handlers * a system should do the authentication/ authorization/ logging or tracking of request and then pass the requests to corresponding handlers
* you want a modular approach to configuring pre-processing and post-processing schemes * you want a modular approach to configuring pre-processing and post-processing schemes

@ -2,6 +2,7 @@
layout: pattern layout: pattern
title: Interpreter title: Interpreter
folder: interpreter folder: interpreter
permalink: /patterns/interpreter/
categories: pattern_cat categories: pattern_cat
tags: pattern_tag tags: pattern_tag
--- ---
@ -16,4 +17,4 @@ language.
interpret, and you can represent statements in the language as abstract syntax interpret, and you can represent statements in the language as abstract syntax
trees. The Interpreter pattern works best when trees. The Interpreter pattern works best when
* the grammar is simple. For complex grammars, the class hierarchy for the grammar becomes large and unmanageable. Tools such as parser generators are a better alternative in such cases. They can interpret expressions without building abstract syntax trees, which can save space and possibly time * the grammar is simple. For complex grammars, the class hierarchy for the grammar becomes large and unmanageable. Tools such as parser generators are a better alternative in such cases. They can interpret expressions without building abstract syntax trees, which can save space and possibly time
* efficiency is not a critical concern. The most efficient interpreters are usually not implemented by interpreting parse trees directly but by first translating them into another form. For example, regular expressions are often transformed into state machines. But even then, the translator can be implemented by the Interpreter pattern, so the pattern is still applicable * efficiency is not a critical concern. The most efficient interpreters are usually not implemented by interpreting parse trees directly but by first translating them into another form. For example, regular expressions are often transformed into state machines. But even then, the translator can be implemented by the Interpreter pattern, so the pattern is still applicable

@ -2,6 +2,8 @@
layout: pattern layout: pattern
title: Introduction title: Introduction
folder: introduction folder: introduction
permalink: /patterns/introduction/
permalink: /patterns/introduction/
categories: pattern_cat categories: pattern_cat
tags: pattern_tag tags: pattern_tag
--- ---
@ -15,4 +17,4 @@ development paradigms.
Reusing design patterns helps to prevent subtle issues that can cause major Reusing design patterns helps to prevent subtle issues that can cause major
problems, and it also improves code readability for coders and architects who problems, and it also improves code readability for coders and architects who
are familiar with the patterns. are familiar with the patterns.

@ -2,6 +2,7 @@
layout: pattern layout: pattern
title: Iterator title: Iterator
folder: iterator folder: iterator
permalink: /patterns/iterator/
categories: pattern_cat categories: pattern_cat
tags: pattern_tag tags: pattern_tag
--- ---
@ -19,4 +20,4 @@ sequentially without exposing its underlying representation.
**Real world examples:** **Real world examples:**
* [java.util.Iterator](http://docs.oracle.com/javase/8/docs/api/java/util/Iterator.html) * [java.util.Iterator](http://docs.oracle.com/javase/8/docs/api/java/util/Iterator.html)

@ -2,6 +2,7 @@
layout: pattern layout: pattern
title: Lazy Loading title: Lazy Loading
folder: lazy-loading folder: lazy-loading
permalink: /patterns/lazy-loading/
categories: pattern_cat categories: pattern_cat
tags: pattern_tag tags: pattern_tag
--- ---
@ -19,4 +20,4 @@ appropriately used.
**Real world examples:** **Real world examples:**
* JPA annotations @OneToOne, @OneToMany, @ManyToOne, @ManyToMany and fetch = FetchType.LAZY * JPA annotations @OneToOne, @OneToMany, @ManyToOne, @ManyToMany and fetch = FetchType.LAZY

@ -2,6 +2,7 @@
layout: pattern layout: pattern
title: Mediator title: Mediator
folder: mediator folder: mediator
permalink: /patterns/mediator/
categories: pattern_cat categories: pattern_cat
tags: pattern_tag tags: pattern_tag
--- ---
@ -16,4 +17,4 @@ other explicitly, and it lets you vary their interaction independently.
* a set of objects communicate in well-defined but complex ways. The resulting interdependencies are unstructured and difficult to understand * a set of objects communicate in well-defined but complex ways. The resulting interdependencies are unstructured and difficult to understand
* reusing an object is difficult because it refers to and communicates with many other objects * reusing an object is difficult because it refers to and communicates with many other objects
* a behavior that's distributed between several classes should be customizable without a lot of subclassing * a behavior that's distributed between several classes should be customizable without a lot of subclassing

@ -2,6 +2,7 @@
layout: pattern layout: pattern
title: Memento title: Memento
folder: memento folder: memento
permalink: /patterns/memento/
categories: pattern_cat categories: pattern_cat
tags: pattern_tag tags: pattern_tag
--- ---
@ -18,4 +19,4 @@ object's internal state so that the object can be restored to this state later.
**Real world examples:** **Real world examples:**
* [java.util.Date](http://docs.oracle.com/javase/8/docs/api/java/util/Date.html) * [java.util.Date](http://docs.oracle.com/javase/8/docs/api/java/util/Date.html)

@ -2,6 +2,7 @@
layout: pattern layout: pattern
title: Model-View-Controller title: Model-View-Controller
folder: model-view-controller folder: model-view-controller
permalink: /patterns/model-view-controller/
categories: pattern_cat categories: pattern_cat
tags: pattern_tag tags: pattern_tag
--- ---
@ -15,4 +16,4 @@ display.
**Applicability:** Use the Model-View-Controller pattern when **Applicability:** Use the Model-View-Controller pattern when
* you want to clearly separate the domain data from its user interface representation * you want to clearly separate the domain data from its user interface representation

@ -2,6 +2,7 @@
layout: pattern layout: pattern
title: Model-View-Presenter title: Model-View-Presenter
folder: model-view-presenter folder: model-view-presenter
permalink: /patterns/model-view-presenter/
categories: pattern_cat categories: pattern_cat
tags: pattern_tag tags: pattern_tag
--- ---
@ -14,4 +15,4 @@ developers to build and test user interfaces.
**Applicability:** Use the Model-View-Presenter in any of the following **Applicability:** Use the Model-View-Presenter in any of the following
situations situations
* when you want to improve the "Separation of Concerns" principle in presentation logic * when you want to improve the "Separation of Concerns" principle in presentation logic
* when a user interface development and testing is necessary. * when a user interface development and testing is necessary.

@ -2,6 +2,7 @@
layout: pattern layout: pattern
title: Multiton title: Multiton
folder: multiton folder: multiton
permalink: /patterns/multiton/
categories: pattern_cat categories: pattern_cat
tags: pattern_tag tags: pattern_tag
--- ---
@ -13,4 +14,4 @@ global point of access to them.
**Applicability:** Use the Multiton pattern when **Applicability:** Use the Multiton pattern when
* there must be specific number of instances of a class, and they must be accessible to clients from a well-known access point * there must be specific number of instances of a class, and they must be accessible to clients from a well-known access point

@ -2,6 +2,7 @@
layout: pattern layout: pattern
title: Naked Objects title: Naked Objects
folder: naked-objects folder: naked-objects
permalink: /patterns/naked-objects/
categories: pattern_cat categories: pattern_cat
tags: pattern_tag tags: pattern_tag
--- ---
@ -20,4 +21,4 @@ everything else is autogenerated by the framework.
**Real world examples:** **Real world examples:**
* [Apache Isis](https://isis.apache.org/) * [Apache Isis](https://isis.apache.org/)

@ -2,6 +2,7 @@
layout: pattern layout: pattern
title: Null Object title: Null Object
folder: null-object folder: null-object
permalink: /patterns/null-object/
categories: pattern_cat categories: pattern_cat
tags: pattern_tag tags: pattern_tag
--- ---
@ -19,4 +20,4 @@ Object is very predictable and has no side effects: it does nothing.
**Applicability:** Use the Null Object pattern when **Applicability:** Use the Null Object pattern when
* you want to avoid explicit null checks and keep the algorithm elegant and easy to read. * you want to avoid explicit null checks and keep the algorithm elegant and easy to read.

@ -2,6 +2,7 @@
layout: pattern layout: pattern
title: Object Pool title: Object Pool
folder: object-pool folder: object-pool
permalink: /patterns/object-pool/
categories: pattern_cat categories: pattern_cat
tags: pattern_tag tags: pattern_tag
--- ---
@ -16,4 +17,4 @@ are in use and which are available.
**Applicability:** Use the Object Pool pattern when **Applicability:** Use the Object Pool pattern when
* the objects are expensive to create (allocation cost) * the objects are expensive to create (allocation cost)
* you need a large number of short-lived objects (memory fragmentation) * you need a large number of short-lived objects (memory fragmentation)

@ -2,6 +2,7 @@
layout: pattern layout: pattern
title: Observer title: Observer
folder: observer folder: observer
permalink: /patterns/observer/
categories: pattern_cat categories: pattern_cat
tags: pattern_tag tags: pattern_tag
--- ---
@ -24,4 +25,4 @@ automatically.
**Real world examples:** **Real world examples:**
* [java.util.Observer](http://docs.oracle.com/javase/8/docs/api/java/util/Observer.html) * [java.util.Observer](http://docs.oracle.com/javase/8/docs/api/java/util/Observer.html)

@ -2,6 +2,7 @@
layout: pattern layout: pattern
title: Poison Pill title: Poison Pill
folder: poison-pill folder: poison-pill
permalink: /patterns/poison-pill/
categories: pattern_cat categories: pattern_cat
tags: pattern_tag tags: pattern_tag
--- ---
@ -17,4 +18,4 @@ graceful shutdown for separate distributed consumption process.
**Real world examples:** **Real world examples:**
* [akka.actor.PoisonPill](http://doc.akka.io/docs/akka/2.1.4/java/untyped-actors.html) * [akka.actor.PoisonPill](http://doc.akka.io/docs/akka/2.1.4/java/untyped-actors.html)

@ -2,6 +2,7 @@
layout: pattern layout: pattern
title: Private Class Data title: Private Class Data
folder: private-class-data folder: private-class-data
permalink: /patterns/private-class-data/
categories: pattern_cat categories: pattern_cat
tags: pattern_tag tags: pattern_tag
--- ---
@ -14,4 +15,4 @@ attributes by encapsulating them in single Data object.
**Applicability:** Use the Private Class Data pattern when **Applicability:** Use the Private Class Data pattern when
* you want to prevent write access to class data members * you want to prevent write access to class data members

@ -2,6 +2,7 @@
layout: pattern layout: pattern
title: Property title: Property
folder: property folder: property
permalink: /patterns/property/
categories: pattern_cat categories: pattern_cat
tags: pattern_tag tags: pattern_tag
--- ---
@ -17,4 +18,4 @@ objects as parents.
**Real world examples:** **Real world examples:**
* [JavaScript](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Inheritance_and_the_prototype_chain) prototype inheritance * [JavaScript](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Inheritance_and_the_prototype_chain) prototype inheritance

@ -2,6 +2,7 @@
layout: pattern layout: pattern
title: Prototype title: Prototype
folder: prototype folder: prototype
permalink: /patterns/prototype/
categories: pattern_cat categories: pattern_cat
tags: pattern_tag tags: pattern_tag
--- ---
@ -19,4 +20,4 @@ instance, and create new objects by copying this prototype.
**Real world examples:** **Real world examples:**
* [java.lang.Object#clone()](http://docs.oracle.com/javase/8/docs/api/java/lang/Object.html#clone%28%29) * [java.lang.Object#clone()](http://docs.oracle.com/javase/8/docs/api/java/lang/Object.html#clone%28%29)

@ -2,6 +2,7 @@
layout: pattern layout: pattern
title: Proxy title: Proxy
folder: proxy folder: proxy
permalink: /patterns/proxy/
categories: pattern_cat categories: pattern_cat
tags: pattern_tag tags: pattern_tag
--- ---
@ -30,4 +31,4 @@ are several common situations in which the Proxy pattern is applicable
**Real world examples:** **Real world examples:**
* [java.lang.reflect.Proxy](http://docs.oracle.com/javase/8/docs/api/java/lang/reflect/Proxy.html) * [java.lang.reflect.Proxy](http://docs.oracle.com/javase/8/docs/api/java/lang/reflect/Proxy.html)
* [Apache Commons Proxy](https://commons.apache.org/proper/commons-proxy/) * [Apache Commons Proxy](https://commons.apache.org/proper/commons-proxy/)

@ -2,6 +2,7 @@
layout: pattern layout: pattern
title: Repository title: Repository
folder: repository folder: repository
permalink: /patterns/repository/
categories: pattern_cat categories: pattern_cat
tags: pattern_tag tags: pattern_tag
--- ---
@ -23,4 +24,4 @@ querying is utilized.
**Real world examples:** **Real world examples:**
* [Spring Data](http://projects.spring.io/spring-data/) * [Spring Data](http://projects.spring.io/spring-data/)

@ -2,6 +2,7 @@
layout: pattern layout: pattern
title: Resource Acquisition Is Initialization title: Resource Acquisition Is Initialization
folder: resource-acquisition-is-initialization folder: resource-acquisition-is-initialization
permalink: /patterns/resource-acquisition-is-initialization/
categories: pattern_cat categories: pattern_cat
tags: pattern_tag tags: pattern_tag
--- ---
@ -12,4 +13,4 @@ tags: pattern_tag
**Applicability:** Use the Resource Acquisition Is Initialization pattern when **Applicability:** Use the Resource Acquisition Is Initialization pattern when
* you have resources that must be closed in every condition * you have resources that must be closed in every condition

@ -2,6 +2,7 @@
layout: pattern layout: pattern
title: Servant title: Servant
folder: servant folder: servant
permalink: /patterns/servant/
categories: pattern_cat categories: pattern_cat
tags: pattern_tag tags: pattern_tag
--- ---
@ -14,4 +15,4 @@ this behavior in the common parent class - it is defined once in the Servant.
**Applicability:** Use the Servant pattern when **Applicability:** Use the Servant pattern when
* when we want some objects to perform a common action and don't want to define this action as a method in every class. * when we want some objects to perform a common action and don't want to define this action as a method in every class.

@ -2,6 +2,7 @@
layout: pattern layout: pattern
title: Service Layer title: Service Layer
folder: service-layer folder: service-layer
permalink: /patterns/service-layer/
categories: pattern_cat categories: pattern_cat
tags: pattern_tag tags: pattern_tag
--- ---
@ -18,4 +19,4 @@ its business logic. The Service Layer fulfills this role.
**Applicability:** Use the Service Layer pattern when **Applicability:** Use the Service Layer pattern when
* you want to encapsulate domain logic under API * you want to encapsulate domain logic under API
* you need to implement multiple interfaces with common logic and data * you need to implement multiple interfaces with common logic and data

@ -2,6 +2,7 @@
layout: pattern layout: pattern
title: Service Locator title: Service Locator
folder: service-locator folder: service-locator
permalink: /patterns/service-locator/
categories: pattern_cat categories: pattern_cat
tags: pattern_tag tags: pattern_tag
--- ---
@ -24,4 +25,4 @@ improves the performance of application to great extent.
* when network hits are expensive and time consuming * when network hits are expensive and time consuming
* lookups of services are done quite frequently * lookups of services are done quite frequently
* large number of services are being used * large number of services are being used

@ -2,6 +2,7 @@
layout: pattern layout: pattern
title: Singleton title: Singleton
folder: singleton folder: singleton
permalink: /patterns/singleton/
categories: pattern_cat categories: pattern_cat
tags: pattern_tag tags: pattern_tag
--- ---
@ -24,4 +25,4 @@ access to it.
**Real world examples:** **Real world examples:**
* [java.lang.Runtime#getRuntime()](http://docs.oracle.com/javase/8/docs/api/java/lang/Runtime.html#getRuntime%28%29) * [java.lang.Runtime#getRuntime()](http://docs.oracle.com/javase/8/docs/api/java/lang/Runtime.html#getRuntime%28%29)

@ -2,6 +2,7 @@
layout: pattern layout: pattern
title: Specification title: Specification
folder: specification folder: specification
permalink: /patterns/specification/
categories: pattern_cat categories: pattern_cat
tags: pattern_tag tags: pattern_tag
--- ---
@ -16,4 +17,4 @@ order
**Applicability:** Use the Specification pattern when **Applicability:** Use the Specification pattern when
* you need to select a subset of objects based on some criteria, and to refresh the selection at various times * you need to select a subset of objects based on some criteria, and to refresh the selection at various times
* you need to check that only suitable objects are used for a certain role (validation) * you need to check that only suitable objects are used for a certain role (validation)

@ -2,6 +2,7 @@
layout: pattern layout: pattern
title: State title: State
folder: state folder: state
permalink: /patterns/state/
categories: pattern_cat categories: pattern_cat
tags: pattern_tag tags: pattern_tag
--- ---
@ -14,4 +15,4 @@ changes. The object will appear to change its class.
**Applicability:** Use the State pattern in either of the following cases **Applicability:** Use the State pattern in either of the following cases
* an object's behavior depends on its state, and it must change its behavior at run-time depending on that state * an object's behavior depends on its state, and it must change its behavior at run-time depending on that state
* operations have large, multipart conditional statements that depend on the object's state. This state is usually represented by one or more enumerated constants. Often, several operations will contain this same conditional structure. The State pattern puts each branch of the conditional in a separate class. This lets you treat the object's state as an object in its own right that can vary independently from other objects. * operations have large, multipart conditional statements that depend on the object's state. This state is usually represented by one or more enumerated constants. Often, several operations will contain this same conditional structure. The State pattern puts each branch of the conditional in a separate class. This lets you treat the object's state as an object in its own right that can vary independently from other objects.

@ -2,6 +2,7 @@
layout: pattern layout: pattern
title: Step Builder title: Step Builder
folder: step-builder folder: step-builder
permalink: /patterns/step-builder/
categories: pattern_cat categories: pattern_cat
tags: pattern_tag tags: pattern_tag
--- ---
@ -11,4 +12,4 @@ The user experience will be much more improved by the fact that he will only see
![alt text](./etc/step-builder.png "Step Builder") ![alt text](./etc/step-builder.png "Step Builder")
**Applicability:** Use the Step Builder pattern when the algorithm for creating a complex object should be independent of the parts that make up the object and how they're assembled the construction process must allow different representations for the object that's constructed when in the process of constructing the order is important. **Applicability:** Use the Step Builder pattern when the algorithm for creating a complex object should be independent of the parts that make up the object and how they're assembled the construction process must allow different representations for the object that's constructed when in the process of constructing the order is important.

@ -2,6 +2,7 @@
layout: pattern layout: pattern
title: Strategy title: Strategy
folder: strategy folder: strategy
permalink: /patterns/strategy/
categories: pattern_cat categories: pattern_cat
tags: pattern_tag tags: pattern_tag
--- ---
@ -17,4 +18,4 @@ that use it.
* many related classes differ only in their behavior. Strategies provide a way to configure a class either one of many behaviors * many related classes differ only in their behavior. Strategies provide a way to configure a class either one of many behaviors
* you need different variants of an algorithm. for example, you might define algorithms reflecting different space/time trade-offs. Strategies can be used when these variants are implemented as a class hierarchy of algorithms * you need different variants of an algorithm. for example, you might define algorithms reflecting different space/time trade-offs. Strategies can be used when these variants are implemented as a class hierarchy of algorithms
* an algorithm uses data that clients shouldn't know about. Use the Strategy pattern to avoid exposing complex, algorithm-specific data structures * an algorithm uses data that clients shouldn't know about. Use the Strategy pattern to avoid exposing complex, algorithm-specific data structures
* a class defines many behaviors, and these appear as multiple conditional statements in its operations. Instead of many conditionals, move related conditional branches into their own Strategy class * a class defines many behaviors, and these appear as multiple conditional statements in its operations. Instead of many conditionals, move related conditional branches into their own Strategy class

@ -2,6 +2,7 @@
layout: pattern layout: pattern
title: Template method title: Template method
folder: template-method folder: template-method
permalink: /patterns/template-method/
categories: pattern_cat categories: pattern_cat
tags: pattern_tag tags: pattern_tag
--- ---
@ -16,4 +17,4 @@ an algorithm without changing the algorithm's structure.
* to implement the invariant parts of an algorithm once and leave it up to subclasses to implement the behavior that can vary * to implement the invariant parts of an algorithm once and leave it up to subclasses to implement the behavior that can vary
* when common behavior among subclasses should be factored and localized in a common class to avoid code duplication. This is good example of "refactoring to generalize" as described by Opdyke and Johnson. You first identify the differences in the existing code and then separate the differences into new operations. Finally, you replace the differing code with a template method that calls one of these new operations * when common behavior among subclasses should be factored and localized in a common class to avoid code duplication. This is good example of "refactoring to generalize" as described by Opdyke and Johnson. You first identify the differences in the existing code and then separate the differences into new operations. Finally, you replace the differing code with a template method that calls one of these new operations
* to control subclasses extensions. You can define a template method that calls "hook" operations at specific points, thereby permitting extensions only at those points * to control subclasses extensions. You can define a template method that calls "hook" operations at specific points, thereby permitting extensions only at those points

@ -2,6 +2,7 @@
layout: pattern layout: pattern
title: Thread Pool title: Thread Pool
folder: thread-pool folder: thread-pool
permalink: /patterns/thread-pool/
categories: pattern_cat categories: pattern_cat
tags: pattern_tag tags: pattern_tag
--- ---
@ -16,4 +17,4 @@ and eliminating the latency of creating new threads.
**Applicability:** Use the Thread Pool pattern when **Applicability:** Use the Thread Pool pattern when
* you have a large number of short-lived tasks to be executed in parallel * you have a large number of short-lived tasks to be executed in parallel

@ -2,6 +2,7 @@
layout: pattern layout: pattern
title: Tolerant Reader title: Tolerant Reader
folder: tolerant-reader folder: tolerant-reader
permalink: /patterns/tolerant-reader/
categories: pattern_cat categories: pattern_cat
tags: pattern_tag tags: pattern_tag
--- ---
@ -15,4 +16,4 @@ changes, the readers must not break.
**Applicability:** Use the Tolerant Reader pattern when **Applicability:** Use the Tolerant Reader pattern when
* the communication schema can evolve and change and yet the receiving side should not break * the communication schema can evolve and change and yet the receiving side should not break

@ -2,6 +2,7 @@
layout: pattern layout: pattern
title: Visitor title: Visitor
folder: visitor folder: visitor
permalink: /patterns/visitor/
categories: pattern_cat categories: pattern_cat
tags: pattern_tag tags: pattern_tag
--- ---
@ -20,4 +21,4 @@ of the elements on which it operates.
**Real world examples:** **Real world examples:**
* [Apache Wicket](https://github.com/apache/wicket) component tree, see [MarkupContainer](https://github.com/apache/wicket/blob/b60ec64d0b50a611a9549809c9ab216f0ffa3ae3/wicket-core/src/main/java/org/apache/wicket/MarkupContainer.java) * [Apache Wicket](https://github.com/apache/wicket) component tree, see [MarkupContainer](https://github.com/apache/wicket/blob/b60ec64d0b50a611a9549809c9ab216f0ffa3ae3/wicket-core/src/main/java/org/apache/wicket/MarkupContainer.java)