PHP PSRs : PSR-12 Extended Coding Style Guide
The PSR-12 (Extended Coding Style Guide) builds upon PSR-1 and provides detailed guidelines for formatting PHP code, making it more readable and maintainable. It is widely adopted by PHP frameworks and projects to ensure a consistent coding style. PSR-12 is an extension of PSR-2 and has the same goal as it, but with a more modern context and new features that follow the evolution of PHP. As PHP 7 has had many changes, the rewritten PSR-2 in a new PSR was necessary to meet all the news available in PHP 7. 1. File Structure & Encoding All PHP files must use UTF-8 encoding without a BOM. PHP files should use at the end in pure PHP files. ✅ Correct: 2. Namespace & Use Declarations The namespace declaration must be on the first line after declare(strict_types=1). Use statements must be placed after the namespace, grouped, and sorted alphabetically. ✅ Correct:
The PSR-12 (Extended Coding Style Guide) builds upon PSR-1 and provides detailed guidelines for formatting PHP code, making it more readable and maintainable. It is widely adopted by PHP frameworks and projects to ensure a consistent coding style.
PSR-12 is an extension of PSR-2 and has the same goal as it, but with a more modern context and new features that follow the evolution of PHP. As PHP 7 has had many changes, the rewritten PSR-2 in a new PSR was necessary to meet all the news available in PHP 7.
1. File Structure & Encoding
- All PHP files must use UTF-8 encoding without a BOM.
- PHP files should use
as the opening tag and should not use?>at the end in pure PHP files.
✅ Correct:
declare(strict_types=1);
❌ Incorrect (Closing tag in a pure PHP file):
declare(strict_types=1);
?>
2. Namespace & Use Declarations
- The namespace declaration must be on the first line after
declare(strict_types=1). - Use statements must be placed after the namespace, grouped, and sorted alphabetically.
✅ Correct:
declare(strict_types=1);
namespace App\Controllers;
use App\Models\User;
use App\Services\AuthService;
use Exception;
❌ Incorrect (Unsorted use statements):
declare(strict_types=1);
namespace App\Controllers;
use Exception;
use App\Services\AuthService;
use App\Models\User;
3. Classes, Properties, and Methods
3.1 Class Declaration
- The opening
{must be on the same line as the class declaration. - Use one blank line before the class definition.
✅ Correct:
namespace App\Models;
class User {
private string $name;
public function getName(): string {
return $this->name;
}
}
❌ Incorrect (Braces on a new line):
namespace App\Models;
class User
{
private string $name;
public function getName(): string
{
return $this->name;
}
}
3.2 Properties
-
Visibility (
public,private,protected) must always be declared. - One property per line.
- Typed properties should be preferred.
✅ Correct:
class User {
private string $name;
private int $age;
}
❌ Incorrect (Missing visibility and multiple properties on one line):
class User {
var $name, $age;
}
3.3 Methods
- The function name must be in camelCase.
- The opening
{must be on the same line. - There should be one blank line before a method.
✅ Correct:
class User {
private string $name;
public function getName(): string {
return $this->name;
}
}
❌ Incorrect (Braces on a new line, no blank line before the method):
class User
{
private string $name;
public function getName(): string
{
return $this->name;
}
}
4. Function and Method Arguments
- No space before the opening parenthesis.
- One space after the comma.
- No trailing comma in the last parameter.
✅ Correct:
function registerUser(string $name, int $age): bool {
return true;
}
❌ Incorrect (Extra spaces):
function registerUser ( string $name , int $age , ): bool {
return true;
}
5. Control Structures (if, for, while, switch)
- Braces are always required.
- Spaces before and after parentheses.
✅ Correct:
if ($age >= 18) {
echo "You are an adult.";
} elseif ($age > 0) {
echo "You are a minor.";
} else {
echo "Invalid age.";
}
❌ Incorrect (Missing braces and spaces):
if($age >= 18) echo "You are an adult.";
elseif($age > 0) echo "You are a minor.";
else echo "Invalid age.";
6. Switch Statements
-
casestatements must be indented. - There must be a break or return in each
case.
✅ Correct:
switch ($status) {
case 'active':
echo "User is active.";
break;
case 'inactive':
echo "User is inactive.";
break;
default:
echo "Unknown status.";
break;
}
❌ Incorrect (Cases not indented, missing break):
switch ($status) {
case 'active':
echo "User is active.";
case 'inactive':
echo "User is inactive.";
default:
echo "Unknown status.";
}
7. Arrays
- Arrays must use the short syntax (
[]instead ofarray()). - Each element in a multiline array should be on a new line.
✅ Correct (Short array syntax, proper formatting):
$users = [
'Alice',
'Bob',
'Charlie',
];
❌ Incorrect (Old syntax, multiple values on one line):
$users = array('Alice', 'Bob', 'Charlie');
8. Visibility in Methods
- Abstract, final, and static must be declared before visibility.
✅ Correct:
class Logger {
public static function log(string $message): void {
echo $message;
}
}
❌ Incorrect (Wrong order of modifiers):
class Logger
{
static public function log(string $message): void
{
echo $message;
}
}
9. Blank Lines and Indentation
- Use 4 spaces for indentation (not tabs).
- One blank line between methods.
- Two blank lines before a class definition.
✅ Correct:
namespace App\Models;
class User {
private string $name;
public function getName(): string {
return $this->name;
}
public function setName(string $name): void {
$this->name = $name;
}
}
❌ Incorrect (No spacing between methods, tabs instead of spaces):
class User
{
private string $name;
public function getName(): string
{
return $this->name;
}
public function setName(string $name): void
{
$this->name = $name;
}
}
Summary of PSR-12
| Rule | Description |
|---|---|
| UTF-8 Encoding | PHP files must use UTF-8 without BOM |
| Namespaces & Use Statements | Must be declared in order and alphabetically sorted |
| Class Declarations | Braces {} must be on the same line as the class definition |
| Properties & Methods | One property per line, methods must use camelCase |
| Function Arguments | No space before (), one space after ,
|
| Control Structures | Always use braces {} for if, else, for, while
|
| Arrays | Must use [] short syntax, multi-line elements on separate lines |
| Blank Lines | One blank line before methods, two before classes |
