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Deign Pattern in Drupal

 What are Design Patterns in General:

Description of communicating objects and classes that are customized to solve a general problem in a particular way.

Why design pattern required:

1 - Design pattern help to speed up the development,
2 - The templates are proven and from the developer's position, the Only implementation is required
3- Encapsulate big ideas in a simpler way
4 -  Each pattern describes a problem which occurs over & over again,

Design Pattern Inforces SOLID Principles:

SOLID is an acronym that stands for the following:

  • Single responsibility principle
  • Open/closed principle
  • Liskov substitution principle
  • Interface segregation principle
  • Dependency inversion principle
Categorization of GOF(Gang of Four Design Patterns)

- Creation - Used to construct objects such that they can be decoupled from their implementation system.

i.e in one class, we put business logic & in another class create the instance of it.

- Structural - Used to form large object structure between many disparate objects

-Behavioural - Used to manage algorithms, relationships, and responsibilities between objects


Design Patterns with Drupal 8 :

Drupal 8 is all about object-oriented PHP and contains concepts like,
  • Dependency Injection
  • Service Container
  • Factory Methods
  • PHP Traits
  • Discovery Methods
  • Strategy Pattern
  • Singleton Pattern
     Design Pattern is 4 Types:

    1 - Singleton Design Pattern
    2 - Factory Design Pattern
    3 - Mediator Design Pattern
    4 - Dependency Injection 

    1-Singleton Design Pattern(The Creational Pattern):

    Singleton Pattern which does not allow to create more than one instance of it.

    • It boosts performance by not allowing the creation of multiple objects to avoid the consumption of more memory by creating multiple objects.

    • Since the class controls the instantiation process, the class has the flexibility to change the instantiation process

    • Ease of Implementation

    2- Factory Design Pattern(The Creational Pattern)

    The Factory Method defines a method, which should be used for creating objects instead of a direct constructor call. The subclass can override this method to change the class of objects that will be created.
    Example: The factory method allow us to create an instance of the class by through the method, Instead of direct object creation. 


    3-Mediator Design Pattern (The behavioral Pattern)

    The mediator is a behavioral design pattern that reduces coupling between components of a program by making them communicate indirectly, through a special mediator object.

    Example: When we post a letter to someone, Then the postman is the mediator only who receives the latter & deliver the destination.

    Drupal 8 Example: Event & subscriber 


    4-Services & Dependency Injection in Drupal 8 :

    Drupal 8 Introduces the concept of services to decouple reusable functionality and makes these services pluggable & replaced by registered them with a service container.

    Services are used to perform operations like accessing the database, sending mail, etc









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