PHP - Best Practices 2019

Daniel Opitz

06 Dec 2019

I think it’s time for a fresh and simplified blog post about the latest PHP Best Practices in 2019 / 2020. A lot has changed within the last time I have written about this topic in 2018.

Principles and rules

Here are the most important rules:

• KISS - Keep it simple, stupid
• YAGNI - You Arent Gonna Need It
• DRY - Don’t repeat yourself
• SOLID - The First 5 Principles of Object Oriented Design
• The Boy Scout Rule - Leave your code better than you found it

Coding styles

• Code must follow PSR-1 and PSR-12. PSR-2 is deprecated.
• Add full PSR-5 DocBlocks for all classes and all methods.

Naming

• Use english names only (class names, method names, comments, variables names, database table and field names, etc…).
• Use class suffixes / prefixes according to PSR Naming Conventions.
• Follow industry best practices for your directory and file structure:
  • thephpleague/skeleton - A skeleton repository for packages
  • pds/skeleton - Names for your root-level directories

Common rules

• All methods must have type declaration and return type declaration.
• Methods without return statement must declared with void as their return type.
• Class properties must have typed properties (PHP 7.4+).
• Don’t mix data types for parameters and return types, except for nullable.
• Don’t extend classes or create abstract classes for the sake of “code reuse”, except for traits with test code only.
• Create final classes by default, except you have to mock it (e.g. repositories).
• Create private methods by default. Don’t create protected methods.
• All method parameters must be used.

Dependency injection

• Use composition over inheritance.
• Declare all class dependencies only within the constructor.
• Don’t inject the container (PSR-11). The service locator is an anti-pattern.
• A constructor can accept only dependencies as object.
• Scalar data types (string, int, float, array) are not allowed for the constructor. Pass them as parameter object.

Tools

Use a static code analyzer to detect bugs and errors. For example:

• phpstan
• Php Inspections EA Extended
• SonarLint Plugin

Read more

• Object Design Style Guide
• Hexagonal Architecture
• http://bestpractices.thecodingmachine.com/
• https://odan.github.io/learn-php/