Structuring Code Effectively

How code is structured can significantly impact both the maintainability and scalability of applications. Traditional methods often involve organizing code into conventional groupings such as by type or functionality. However, as applications grow in complexity and size, these traditional structures can lead to issues such as tight coupling and reduced readability. This post explores advanced strategies for breaking free from conventional groupings and minimizing access to ensure maximum clarity and maintainability.

Breaking Free from Conventional Groupings

Traditionally, code is organized by type—models here, controllers there, and views somewhere else. While this approach might seem logical, it often leads to scattered codebases where related functionalities are not co-located, making the code harder to follow and manage. A more effective approach involves grouping by feature or domainuse-case. This method, often referred to as modular or domain-driven design, organizes code around business domains or features, thus keeping all related code in a single, discoverable location.

●??Feature-Based Structure: Organize directories and files around specific features or business logic. For instance, instead of having separate directories for controllers, views, and models, have a single directory for each distinct feature like ‘InvoiceManagement’ or ‘UserProfiles’.

●???Advantages: This approach makes the codebase more navigable as developers can easily find all code related to a specific feature in one place. It also enhances the modularity of the code, making it easier to scale and update.

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Consider the unrelated nature of ProductRepository and UserRepository. Grouping them merely because they are repositories overlooks the distinct domain problems they solve. A more enlightened approach groups ProductEntity, ProductService, and ProductRepository based on their coupling and cohesion - they change together, they stay together. This encapsulation guards the domain knowledge and ensures that each component serves a single, focused purpose(Figure 4-4).

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Figure 4-4. Domain driven code structure

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Minimizing Access for Maximum Clarity

Encapsulation is a fundamental concept in object-oriented programming that involves restricting direct access to some of an object’s components, which can lead to increased security and robustness. By minimizing access to classes, methods, or variables, you not only protect the integrity of the data but also improve the understandability of the code by reducing its complexity.

A pivotal strategy in preventing your codebase from becoming a "big ball of mud" is restricting access levels. The liberal use of public access modifiers is a common pitfall; it invites unnecessary dependencies and entanglements. Instead, package your classes by domain/context, allowing interaction with other packages exclusively through well-defined interfaces(Figure 4-5). This discipline in access control is crucial for maintaining a clean, modular architecture.

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Figure 4-5. Good and bad modularization diagram

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Effective architecture is not just about decomposition into smaller components; it's about how these components interact within their bounded contexts. Clear boundaries are essential for maintaining domain integrity and ensuring components cooperate without undue reliance on one another. By breaking away from conventional groupings and minimizing access, developers can create more robust, secure, and clean applications. These practices not only improve the immediate readability and maintainability of code but also ensure that the application remains manageable as it scales.

Adopting these principles requires a shift in mindset from traditional methods, but the long-term benefits in terms of code quality and developer productivity are well worth the effort.

Practical Application: A Case Study

To illustrate these concepts, I embarked on an opensource project to design a monolithic application built on the foundations of modularity. This project serves as a practical example of how to apply the principles discussed, from domain-driven design to effective unit testing.

For a deeper dive into this project, including a walkthrough of its structure and the architectural decisions made, I invite you to check out the project and the accompanying video. This visual guide reinforces the lessons shared in this section and demonstrates how theoretical principles translate into real-world applications.

https://github.com/apssouza22/trading-system