general

General concepts

PHP tags

• The first line of all .php files should be exactly "<?php"
• Never use the closing PHP tag (?>)
• Never use PHP short tags

Standards

• All files must only use UTF-8, without BOM
• Always use UTC timezone to store date and time

Side effects

• Every .php library file should contain one class exactly
• Every .php library file should be side effect free

Naming convention

• Singular words (e.g. item, stylesheet, user) should be used throughout files and code instead of plurals
• Avoid Hungarian Notation, where file/variable names that indicate their type

Functions

• Limit function length
• Ensure return points are consistent
• A function should only ever do one thing, as indicated by its name
• Functions should either mutate or query the system, never both

Variables

• Use camelCase for variable naming
• Never use global variables
• Properties should always be declared
• Variables should always be declared at the top of the block they are used in

Open closed principle

• Avoid using final keyword unless necessary
• Avoid calling functions in global namespace