Design PatternsOksana Demediuk

Design pattern is a general reusable solution to a commonly occurring problem in software design.

A design pattern is not a finished design that can be transformed directly into code. It is a description or template for how to solve a problem that can be used in many different situations.

What is Design Pattern

To design a new software system quickly and efficiently.

To understand a existing software system.

Why Design Patterns

Creational Design pattern– Object creation.

Structural design patterns– Relationship between entities.

Behavioral design patterns– Communication between objects.

Types of Design Pattern

Periodic Table of Patterns

Ensure a class has only one instance, and provide a global point of access to it.

Encapsulated “just-in-time initialization” or “initialization on first use”.

Type : Creational pattern.

Singleton Design Pattern

The strategy pattern (also known as the policy

pattern) is a particular software design pattern,

whereby algorithms can be selected at runtime.

Type : Behavioral pattern.

Strategy Design pattern

A facade is an object that provides a simplified interface to a larger body of code, such as a class library.

Type: Structural Design Pattern.

Facade pattern

Speed up the development process by providing tested, proven development paradigms.

Help to prevent subtle issues that can cause major problems, code readability.

Provide general solutions, documented in a format that doesn't require specifics tied to a particular problem.

Allow developers to communicate using well-known, well understood names for software interactions.

A standard solution to a common programming problem enable large scale reuse of software

Design patterns advantages