Design Pattern: Elements & Types for Software Developments

What is a Design Pattern?

Design pattern serves as a solution to common errors during the software development process.

With this pattern, the development team can minimize the effort required to design a solution from scratch every time they encounter a similar challenge.

Overall, it is similar to a blueprint ready for use to solve repetitive design problems during the coding process. 

However, it's essential to note that design patterns are not code snippets. It usually resembles structural concepts or guidelines that assist the team in understanding interactions and relationships between objects in a system. 

Therefore, it can help developers avoid common design issues, thereby accelerating the overall development process.

The Differences Between Design Patterns and Algorithms

Unfortunately, many people still believe that software design patterns and programming algorithms are the same concepts because both provide solutions to coding problems. 

However, it's crucial to understand that both have different functions and applications. Algorithms are generally used to outline the steps required to achieve a specific goal.

On the other hand, software design patterns describe solutions at a higher level of abstraction, and you can examine the results of the solution along with the features used. 

Design Pattern Elements

Here are the elements you should include within the pattern.

• Name or Term: Defining a specific term or name to define a particular design problem, creates a uniform foundation of understanding.
• Brief Description: Provide a brief description of the pattern, succinctly explaining the problem it addresses and the solution it presents.
• Structure: Illustrating the structure that forms the relationships between elements in the pattern, aiding understanding of how components interact.
• Implementation: Presenting concrete examples in the form of code implementation, using a specific programming language. These examples help developers better understand how to apply the pattern in practice.

Benefits of Design Patterns in Software Development

In addition to understanding what is a design pattern, it's also crucial for you to note the benefits of these design templates. They are:

1. Structured Code Writing

For developers, software design patterns are a highly beneficial solution to make code writing more structured and organized by following established design principles.

2. Solidifying Program Architecture

It provides a clear structure and guidelines for organizing components within a system. Consequently, developers can design a more robust and structured program architecture.

3. Providing Tested Solutions

They offer proven and effective problem-solving solutions in software development with high-level approaches.

4. Improving Readability

Code written based on a designated pattern tends to be more readable and evaluable, as it establishes conventions and specific structures that are widely recognized, creating consistency in the code. 

Developers can read and understand the code structure without delving into every line in detail.

5. Encouraging Code Reusability Concepts:

Software design patterns allow the abstraction of specific components and separate the implementation details from how these components are used. 

This enables these components to be reused in various situations without having to change existing code.

Design Pattern Types

Several factors influence the grouping of pattern types, including complexity, details, and the extent of their use. Overall, there are three design pattern types that are most commonly used. 

1. Creational Pattern

In general, this design pattern type serves to solve problems encountered in the process of creating an object. 

Creational patterns focus on how objects and instances are created, making the object initialization process more objective. This pattern can be divided into 5 different categories, namely:

• Builder: Creates complex objects from simple basic objects gradually.
• Factory Method: Also called a virtual constructor that defines an abstract class in the object creation process.
• Abstract Factory: Defines an interface or abstract classification without specifying a sub-class when creating an object.
• Singleton: Ensures that each class has only one instance and provides global access to that instance. There are two forms of the singleton pattern: early instantiation and lazy instantiation.
• Prototype: Developers can copy objects with an available prototype instance. The creation of new objects can also be customized as needed.

2. Structural Pattern

This pattern aims to solve problems in the arrangement of compositions between classes and objects. 

In other words, these patterns focus on how classes and objects are combined into a larger and more complex structure. Generally, structural patterns can be divided into 7 other types, namely:

• Bridge:  Divides large-sized classes into two hierarchies: abstraction and implementation. 
• Composite: Transforms objects into a structured tree so that the entire hierarchy of objects is visible.
• Adapter/Wrapper: Acts as an intermediary between two incompatible interfaces, allowing them to interact.
• Facade: Provides a simple interface for clients to interact with a complex system.
• Decorator: Adds new functionality to existing objects without changing their underlying structure by placing additional objects around the existing ones.
• Flyweight: Aims to reduce storage space usage by sharing components among objects to save resources.
• Proxy: Provides a substitute or representative for another object. The proxy object acts as an intermediary between the client and the actual object, allowing additional control such as lazy loading, access control, or logging.

3. Behavioral Pattern

Behavioral patterns can help solve problems in communication between objects. In other words, behavioral patterns offer solutions for organizing control flow between objects and managing dependency relationships within the system. These patterns can be divided into 11 core types, namely:

• Command: Also known as Action or Transition, it transforms requests into objects containing all the information related to the request.
• Interpreter: To interpret and evaluate language syntax and interpret the meaning of sentences in a specific language.
• Iterator: Also known as Cursor, it functions to access elements of a collection object sequentially.
• Chain of Responsibility: Patterns that create a chain for sending requests by separating the sender and receiver based on the dispatch.
• Mediator: Acts as a mediator that defines the interaction flow of objects with classes or other objects. This pattern can reduce the complexity of communication between several objects.
• Memento: A pattern that can help handle errors by restoring the original state of an object without violating rules.
• Observer: Known as Dependents or Publish-Subscribe. If there is a change in the status of an object, all dependencies within it will receive notifications automatically.
• State: This pattern is used when there is an object whose behavior changes based on internal conditions and changes the class status.
• Strategy/Policy: Defines and summarizes each algorithm in separate classes.
• Template Method: Defines the algorithm framework into a base class. Subclasses can define these steps without changing the algorithm structure.
• Visitor: A pattern that helps developers define new operations without changing element class.

Patterns at the basic level are often referred to as idioms, which generally apply to a specific programming language.

On the other hand, the most commonly used patterns are called architectural patterns, which can be used in almost all programming languages or even for designing the entire structure of an application.