Software Design Patterns in 10 Minutes

A design pattern is a general repeatable solution to a commonly occurring problem in software design. A design pattern isn’t 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.

Design patterns can speed development by providing tested, proven development paradigms. Effective software design requires considering issues that may not become visible until later in the implementation. Reusing design patterns helps prevent subtle issues that can cause significant problems and improves code readability for coders and architects familiar with the practices.

There are several design patterns, including creational, structural, and behavioral. Creational practices deal with object creation mechanisms, trying to create objects in a manner suitable to the situation. Structural patterns deal with object composition, building relationships between objects to form larger structures. Behavioral patterns focus on communication between objects, what goes on between things, and how they operate together.

Here is a list of ten design patterns that are commonly used in software engineering:

1. Singleton pattern: Ensures that a class has only one instance and provides a global point of access to it.
2. Factory pattern: Creates objects without specifying the exact class to create.
3. Abstract factory pattern: Provides an interface for creating families of related or dependent objects without specifying their concrete classes.
4. Builder pattern: Separates the construction of a complex object from its representation, allowing the same construction process to create various models.
5. Prototype pattern: Creates new objects by copying existing objects.
6. Adapter pattern: Allows classes with incompatible interfaces to work together by wrapping their interface around that of an already existing class.
7. Bridge pattern: Separates an abstraction from its implementation, allowing the two to vary independently.
8. Decorator pattern: Adds new behavior to an existing object dynamically by wrapping it in a decorator object.
9. Visitor pattern: Allows a new operation to be added to a class without changing the class.
10. Observer pattern: This allows one object to notify other objects of events, allowing the objects to be loosely coupled and to be able to evolve independently.

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