Final Thoughts

All these principles come together as one, they often overlap. It's nice when you know the theory like SOLID principles because it makes it easier to make good code. Then you also have strong arguments behind your code, for example in code review. All the rules are aimed at making the code easy to understand and maintain.

SOLID is one of the many good practices that help us write clean code. I've written about the Boy Scout Rule before. But that's not all, there are many other rules and standards to follow. Let me just mention them:

  • PSR (PHP Standards Recommendations) — PHP Framework Interop Group (PHP-FIG) is a group of people associated with the largest PHP projects who jointly develop PSR. I think every PHP programmer should know coding styles standards PSR-1 and PSR-12 (formerly PSR-2). You can find all the current sets of standards here
  • KISS (Keep It Simple Stupid) — Don't complicate the code. The code should be its documentation itself. Any new programmer on the team should be able to get into the project quickly.
  • DRY (Don’t Repeat Yourself) — Do not code using the Copy-Paste principle (there is no such rule). See that the same code repeats in several places? Extract code for a separate function.
  • YAGNI (You Aren’t Gonna Need It) — 17th-century German philosopher Johannes Clauberg formulated a principle called Occam's Razor (I was also surprised Ockham was not its author ;) ) “entities should not be multiplied beyond necessity". I think this sentence expresses the YAGNI principle well. We should not write code “for the future”. Such code is not needed at the moment.
  • GRASP (General Responsibility Assignment Software Patterns) — is a large set of rules about which I could write a separate article. These are the basic principles that we should follow when creating object design and responsibility assignments. It consists of Information Expert, Controller, Creator, High Cohesion, Low Coupling, Pure Fabrication, Polymorphism, Protected Variations and Indirection.

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