What is PSR?
PSR is a standard established by PHP-FIG(PHP Framework Interop Group).
PSR consists of several standards such as PSR-1, PSR-2 and PSR-4.
PSR-0 and PSR-4 are coding standards for PHP’s autoloaders, PSR-1 and PSR-2 are basic coding standards.
PHP code MUST use only UTF-8 without BOM(Byte Order Mark).
PSR-1 Basic Coding Standard, defines basic parts of PHP coding
- Only
<?php ?>or<?= ?>are allowed for PHP tags - Files must be in UTF-8 without BOM(Byte Order Mark)
- Namespaces and class names must follow the standards in PSR-0 and PSR-4
- Class names must be defined in
UpperCamelCase - Class variables must be defined in
UPPER_SNAKE_CASE - Method names must be defined in
camelCase
// defining normal properties in camelCase
// defining static properties in UpperCamelCase
// Class constants MUST be declared in all upper case with underscore separators
class Something
{
public $normalPropterty;
public static $StaticProperty;
const VERSION = '1.0';
const DATE_APPROVED = '2000-12-01';
}
PSR-2 Coding style Guide, an extension of PSR-1
- You must follow PSR-1 coding standards
- 4 spaces must be used for indents. Using tabs is not allowed
- There is no limit to line length, but it should be under 120 characters, and best if under 80
- You must put a newline before curly braces for classes and methods
- Methods and properties must be defined with
abstract/finalfirst, followed withpublic/protected, and finallystatic. - You must not put a newline before curly braces in conditional statements
- You must not put any spaces before ( and ) in conditional statements
PSR-12: Extended Coding Style, is now recommended for PSR-2.
- .php files must use Unix LF(linefeed) line
\nending only. - .php files must end with a non-blank line.
- closing
?>tag must be omitted from .php files containing only php. - Compound namespaces with a depth of more than two MUST NOT be used.
namespace SubnamespaceOne\Anothernamespace\ClassA;
<?php
/**
* This file contains an example of coding styles.
*/
declare(strict_types=1);
// MUST be one blank line after the namespace declaration
namespace Vendor\Package;
// MUST be one blank line after the block of use declarations.
use Vendor\Package\{ClassA as A, ClassB, ClassC as C};
use Vendor\Package\SomeNamespace\ClassD as D;
use function Vendor\Package\{functionA, functionB, functionC};
use const Vendor\Package\{ConstantA, ConstantB, ConstantC};
use Vendor\Package\FirstTrait;
// Opening braces for classes MUST go on the next line, and closing braces MUST go on the next line after the body.
class Foo extends Bar implements FooInterface
{
// use keyword used inside the classes to implement traits MUST be declared on the next line after the opening brace.
use FirstTrait;
// Opening braces for methods MUST go on the next line, and closing braces MUST go on the next line after the body.
public function sampleFunction(int $a, int $b = null): array
{
if ($a === $b) {
bar();
} elseif ($a > $b) {
$foo->bar($arg1);
} else {
BazClass::bar($arg2, $arg3);
}
}
// abstract and final MUST be declared before the visibility;
// static MUST be declared after the visibility.
final public static function bar()
{
// method body
}
}