Connecting your application’s core logic (the domain objects) to a persistent store (like a database) is a fundamental task. However, directly embedding database logic within your domain objects can lead to tight coupling, making your code harder to test, maintain, and evolve. How can we keep these concerns separate?
Enter the Data Mapper pattern. As Martin Fowler describes in “Patterns of Enterprise Application Architecture” (P of EAA, page 165):
A layer of Mappers that moves data between objects and a database while keeping them independent of each other and the mapper itself.
Software development is often about managing complexity and change. As applications grow, how do we add new features without breaking existing ones? How do we ensure our code remains maintainable, flexible, and robust? Two core principles from the SOLID acronym offer powerful guidance: the Open/Closed Principle (OCP) and the Liskov Substitution Principle (LSP).
Let’s dive into what these principles mean, why they matter, and how TypeScript helps us implement them effectively.
Writing software that works is one thing; writing software that is easy to understand, maintain, extend, and test is another. As applications grow in complexity, adhering to sound design principles becomes crucial for long-term success and sanity. Two fundamental sets of guidelines stand out: the SOLID principles for object-oriented design and the DRY principle.
Let’s break down these concepts to understand how they help us build better software.
The SOLID Principles Coined by Robert C.