3 Design Patterns Every Developer Should Learn

The article treats design patterns as high-level ways to approach recurring software problems, not as code itself. It says they help make code easier to adapt, create a shared vocabulary, and become more important as developers build larger systems and microservices.

Reading notes

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• Design patterns are described as recurring approaches to common problems in software engineering, not as code.
• They are presented as useful for making code more readable and adaptable.
• They also create a shared vocabulary, so teams can communicate with names like Singleton.
• The article recommends three patterns to learn: Strategy, Singleton, and Observer.
• Strategy is used to choose between algorithms at runtime and supports the open-closed principle.
• The delivery example shows separate strategies for bike, car, rail, air, and ship instead of one growing class.
• Singleton is used when only one instance of a class is needed and when shared resources must be controlled.
• The article mentions configuration settings, in-memory data, and comparators as examples of singleton use.
• Observer is presented as a one-to-many relationship where one object notifies others about changes.
• Examples given for Observer include Netflix subscriptions, email notifications, news alerts, Redux, CI builds, Kafka, RabbitMQ, Amazon SNS, and NATS.
• The article warns that design patterns can be overused and should be chosen only when they fit the project.
• It stresses that knowing a pattern’s name is not the same as understanding its constraints and tradeoffs.
• The origin of the idea is traced to Christopher Alexander and later to the 1994 book by the Gang of Four, which popularized design patterns in software development.