PSR-2: Coding Style Guide

1. General

Files

All PHP files MUST use theUnix LF (linefeed) line ending. ("\n")

All PHP files MUST end with a single blank line.

The closing ?> tag MUST be omitted from files containing only PHP.

Lines

There MUST NOT be a hard limit on line length.

The soft limit on line length MUST be 120 characters; automated style checkers MUST warn but MUST NOT error at the soft limit.

Lines SHOULD NOT be longer than 80 characters; lines longer than that SHOULD be split into multiple subsequent lines of no more than 80 characters each.

There MUST NOT be trailing whitespace at the end of non-blank lines.

Blank lines MAY be added to improve readability and to indicate related blocks of code.

There MUST NOT be more than one statement per line.

Indenting

Code MUST use an indent of 4 spaces, and MUST NOT use tabs for indenting.

N.b.: Using only spaces, and not mixing spaces with tabs, helps to avoid problems with diffs, patches, history, and annotations. The use of spaces also makes it easy to insert fine-grained sub-indentation for inter-line alignment.

Keywords and True/False/Null

PHP keywords MUST be in lower case.

The PHP constants true, false, and null MUST be in lower case.

2. Control Structures

The general style rules for control structures are as follows:

  1. There MUST be one space after the control structure keyword
  2. There MUST NOT be a space after the opening parenthesis
  3. There MUST NOT be a space before the closing parenthesis
  4. There MUST be one space between the closing parenthesis and the opening brace
  5. The structure body MUST be indented once
  6. The closing brace MUST be on the next line after the body

The body of each structure MUST be enclosed by braces. This standardizes how the structures look, and reduces the likelihood of introducing errors as new lines get added to the body.

if, elseif, else

An if structure looks like the following. Note the placement of parentheses, spaces, and braces; and that else and elseif are on the same line as the closing brace from the earlier body.

<?php
if ($expr1) {
    // if body
} elseif ($expr2) {
    // elseif body
} else {
    // else body;
}

The keyword elseif SHOULD be used instead of else if so that all control keywords look like single words.

switch, case

Aswitchstructure looks like the following. Note the placement of parentheses, spaces, and braces. Thecasestatement MUST be indented once fromswitch, and thebreakkeyword (or other terminating keyword) MUST be indented at the same level as thecasebody. There MUST be a comment such as// no breakwhen fall-through is intentional in a non-emptycasebody.

<?php
switch ($expr) {
    case 0:
        echo 'First case, with a break';
        break;
    case 1:
        echo 'Second case, which falls through';
        // no break
    case 2:
    case 3:
    case 4:
        echo 'Third case, return instead of break';
        return;
    default:
        echo 'Default case';
        break;
}
while, do while

Awhilestatement looks like the following. Note the placement of parentheses, spaces, and braces.

<?php
while ($expr) {
    // structure body
}

Similarly, ado whilestatement looks like the following. Note the placement of parentheses, spaces, and braces.

<?php
do {
    // structure body;
} while ($expr);
for

Aforstatement looks like the following. Note the placement of parentheses, spaces, and braces.

<?php
for ($i = 0; $i < 10; $i++) {
    // for body
}
foreach

Aforeachstatement looks like the following. Note the placement of parentheses, spaces, and braces.

<?php
foreach ($iterable as $key => $value) {
    // foreach body
}
try, catch

Atry catchblock looks like the following. Note the placement of parentheses, spaces, and braces.

<?php
try {
    // try body
} catch (FirstExceptionType $e) {
    // catch body
} catch (OtherExceptionType $e) {
    // catch body
}

3. Namespace and Use Declarations

When present, there MUST be one blank line after the namespace declaration.

When present, all use declarations MUST go after the namespace declaration.

There MUST be one use keyword per declaration.

There MUST be one blank line after the use block.

For example:

<
?php
namespace Vendor\Package;


use FooClass;
use BarClass as Bar;
use OtherVendor\OtherPackage\BazClass;


// ... additional PHP code ...

4. Class, Properties, and Methods

The term “class” refers to all classes, interfaces, and traits.

Extends and Implements

The extends and implements keywords MUST be declared on the same line as the class name.

The opening brace for the class MUST go on its own line; the closing brace for the class MUST go on the next line after the body.

<
?php
namespace Vendor\Package;


use FooClass;
use BarClass as Bar;
use OtherVendor\OtherPackage\BazClass;


class ClassName extends ParentClass implements \ArrayAccess, \Countable
{
    // constants, properties, methods
}

Lists of implements MAY be split across multiple lines, where each subsequent line is indented once. When doing so, the first item in the list MUST be on the next line, and there MUST be only one interface per line.

<
?php
namespace Vendor\Package;


use FooClass;
use BarClass as Bar;
use OtherVendor\OtherPackage\BazClass;


class ClassName extends ParentClass implements
    \ArrayAccess,
    \Countable,
    \Serializable
{
    // constants, properties, methods
}
Properties

Visibility MUST be declared on all properties.

The var keyword MUST NOT be used to declare a property.

There MUST NOT be more than one property declared per statement.

Property names SHOULD NOT be prefixed with a single underscore to indicate protected or private visibility.

A property declaration looks like the following.

<
?php
namespace Vendor\Package;


class ClassName
{
    public $foo = null;
}
Methods

Visibility MUST be declared on all methods.

Method names SHOULD NOT be prefixed with a single underscore to indicate protected or private visibility.

Method names MUST NOT be declared with a space after the method name. The opening brace MUST go on its own line, and the closing brace MUST go on the next line following the body. There MUST NOT be a space after the opening parenthesis, and there MUST NOT be a space before the closing parenthesis.

A method declaration looks like the following. Note the placement of parentheses, commas, spaces, and braces:

<
?php
namespace Vendor\Package;


class ClassName
{
    public function fooBarBaz($arg1, 
&
$arg2, $arg3 = [])
    {
        // method body
    }
}
Method Arguments

In the argument list, there MUST NOT be a space before each comma, and there MUST be one space after each comma.

Method arguments with default values MUST go at the end of the argument list.

<
?php
namespace Vendor\Package;


class ClassName
{
    public function foo($arg1, 
&
$arg2, $arg3 = [])
    {
        // method body
    }
}

Argument lists MAY be split across multiple lines, where each subsequent line is indented once. When doing so, the first item in the list MUST be on the next line, and there MUST be only one argument per line.

When the argument list is split across multiple lines, the closing parenthesis and opening brace MUST be placed together on their own line with one space between them.

<
?php
namespace Vendor\Package;


class ClassName
{
    public function aVeryLongMethodName(
        ClassTypeHint $arg1,
&
$arg2,
        array $arg3 = []
    ) {
        // method body
    }
}
Abstract

When present, the abstract and final declarations MUST precede the visibility declaration.

When present, the static declaration MUST come after the visibility declaration.

<
?php
namespace Vendor\Package;


abstract class ClassName
{
    protected static $foo;


    abstract protected function zim();


    final public static function bar()
    {
        // method body
    }
}
Method and Function Calls

When making a method or function call, there MUST NOT be a space between the method or function name and the opening parenthesis, there MUST NOT be a space after the opening parenthesis, and there MUST NOT be a space before the closing parenthesis. In the argument list, there MUST NOT be a space before each comma, and there MUST be one space after each comma.

<
?php
bar();
$foo-
>
bar($arg1);
Foo::bar($arg2, $arg3);

Argument lists MAY be split across multiple lines, where each subsequent line is indented once. When doing so, the first item in the list MUST be on the next line, and there MUST be only one argument per line.

<
?php
$foo-
>
bar(
    $longArgument,
    $longerArgument,
    $muchLongerArgument
);

5. Cloure

Cloure: anonymouse functions

Closure {
/* Methods */
private __construct ( void )
public static Closure bind ( Closure $closure , object $newthis [, mixed $newscope = "static" ] )
public Closure bindTo ( object $newthis [, mixed $newscope = "static" ] )
public mixed call ( object $newthis [, mixed $... ] )
public static Closure fromCallable ( callable $callable )
}

Closures MUST be declared with a space after thefunctionkeyword, and a space before and after theusekeyword.

The opening brace MUST go on the same line, and the closing brace MUST go on the next line following the body.

There MUST NOT be a space after the opening parenthesis of the argument list or variable list, and there MUST NOT be a space before the closing parenthesis of the argument list or variable list.

In the argument list and variable list, there MUST NOT be a space before each comma, and there MUST be one space after each comma.

Closure arguments with default values MUST go at the end of the argument list.

A closure declaration looks like the following. Note the placement of parentheses, commas, spaces, and braces:

<?php
$closureWithArgs = function ($arg1, $arg2) {
    // body
};

$closureWithArgsAndVars = function ($arg1, $arg2) use ($var1, $var2) {
    // body
};

Argument lists and variable lists MAY be split across multiple lines, where each subsequent line is indented once. When doing so, the first item in the list MUST be on the next line, and there MUST be only one argument or variable per line.

When the ending list (whether of arguments or variables) is split across multiple lines, the closing parenthesis and opening brace MUST be placed together on their own line with one space between them.

The following are examples of closures with and without argument lists and variable lists split across multiple lines.

<?php
$longArgs_noVars = function (
    $longArgument,
    $longerArgument,
    $muchLongerArgument
) {
    // body
};

$noArgs_longVars = function () use (
    $longVar1,
    $longerVar2,
    $muchLongerVar3
) {
    // body
};

$longArgs_longVars = function (
    $longArgument,
    $longerArgument,
    $muchLongerArgument
) use (
    $longVar1,
    $longerVar2,
    $muchLongerVar3
) {
    // body
};

$longArgs_shortVars = function (
    $longArgument,
    $longerArgument,
    $muchLongerArgument
) use ($var1) {
    // body
};

$shortArgs_longVars = function ($arg) use (
    $longVar1,
    $longerVar2,
    $muchLongerVar3
) {
    // body
};

Note that the formatting rules also apply when the closure is used directly in a function or method call as an argument.

<?php
$foo->bar(
    $arg1,
    function ($arg2) use ($var1) {
        // body
    },
    $arg3
);

6. Conclusion

There are many elements of style and practice intentionally omitted by this guide. These include but are not limited to:

  • Declaration of global variables and global constants

  • Declaration of functions

  • Operators and assignment

  • Inter-line alignment

  • Comments and documentation blocks

  • Class name prefixes and suffixes

  • Best practices

Future recommendations MAY revise and extend this guide to address those or other elements of style and practice.

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