PSR-2 Guia de Estilo de Codificação

#Guia de Estilo de Codificação

Este guia se estende e se expande no PSR-1, o padrão básico de codificação.

A intenção deste guia é reduzir o atrito cognitivo ao escanear códigos de diferentes autores. Para isso, são enumerados um conjunto compartilhado de regras e expectativas sobre como formatar o código PHP

As regras de estilo aqui são derivadas de semelhanças entre os vários projetos de membros. Quando vários autores colaboram em vários projetos, ajuda ter um conjunto de diretrizes a serem usadas entre todos esses projetos. Assim, o benefício deste guia não está nas próprias regras, mas no compartilhamento dessas regras.

As palavras-chave “MUST”, “MUST NOT”, “REQUIRED”, “SHALL”, “SHALL NOT”, “SHOULD”, “SHOULD NOT”, “RECOMMENDED”, “MAY”, and “OPTIONAL” nesse documento devem ser interpretadas como descrito na RFC 2119.

1. Visão Geral

O código DEVE seguir um PSR de “Guia de Estilo de Codificação” [PSR-1].
O código DEVE utilizar 4 espaços para indentação, não tabs.
NÃO DEVE haver um limite rígido no comprimento da linha; o limite suave DEVE ter 120 caracteres; linhas devem ter 80 caracteres ou menos.
Deve haver uma linha em branco após a declaração namespace, e DEVE haver uma linha em branco após o bloco de declarações use.
A abertura de chaves para as classes DEVE ir na próxima linha, e fechamento das chaves deve ir na próxima linha após o corpo.
A abertura de chaves para os métodos DEVE ser feita na próxima linha, e o fechamento das chaves DEVE ser feito na próxima linha após o corpo.
A visibilidade DEVE ser declarada em todas as propriedades e métodos; abstract e final DEVEM ser declarados antes da visibilidade; static DEVE ser declarado depois da visibilidade.
Palavras-chave da estrutura de controle DEVEM ter um espaço depois delas; Chamadas de método e função NÃO DEVEM.
A abertura de chaves para estruturas de controle DEVEM ir na mesma linha, e o fechamento de chaves DEVE ser feito na linha após o corpo.
A abertura de parênteses para estruturas de controle NÃO DEVE ter um espaço depois deles, e o fechamento de parênteses para estruturas de controle NÃO DEVE ter um espaço antes.

1.1. Exemplo

Este exemplo engloba algumas das regras abaixo como uma visão geral rápida:

<?php
namespace Vendor\Package;

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

class Foo extends Bar implements FooInterface
{
    public function sampleMethod($a, $b = null)
    {
        if ($a === $b) {
            bar();
        } elseif ($a > $b) {
            $foo->bar($arg1);
        } else {
            BazClass::bar($arg2, $arg3);
        }
    }

    final public static function bar()
    {
        // corpo do método
    }
}

2. Geral

2.1. Padrão Básico de Codificação

O Código DEVE seguir todas as regras descritas no PSR-1.

2.2. Arquivos

Todos os arquivos PHP DEVEM usar o Unix LF (linefeed).

Todos os arquivos PHP devem terminar com uma única linha em branco.

A tag de fechamento ?> DEVE ser omitida dos arquivos contendo apenas PHP.

2.3. Linhas

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.

2.4. 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.

2.5. Keywords and True/False/Null

PHP keywords MUST be in lower case.

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

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. Classes, Properties, and Methods

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

4.1. 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
}

4.2. 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;
}

4.3. 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
    }
}

4.4. 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
    }
}

4.5. `abstract`, `final`, and `static`

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
    }
}

4.6. 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);

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

5. Control Structures

The general style rules for control structures are as follows:

There MUST be one space after the control structure keyword
There MUST NOT be a space after the opening parenthesis
There MUST NOT be a space before the closing parenthesis
There MUST be one space between the closing parenthesis and the opening brace
The structure body MUST be indented once
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.

5.1. `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.

5.2. `switch`, `case`

A switch structure looks like the following. Note the placement of parentheses, spaces, and braces. The case statement MUST be indented once from switch, and the break keyword (or other terminating keyword) MUST be indented at the same level as the case body. There MUST be a comment such as // no break when fall-through is intentional in a non-empty case body.

<?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;
}

5.3. `while`, `do while`

A while statement looks like the following. Note the placement of parentheses, spaces, and braces.

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

Similarly, a do while statement looks like the following. Note the placement of parentheses, spaces, and braces.

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

5.4. `for`

A for statement looks like the following. Note the placement of parentheses, spaces, and braces.

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

5.5. `foreach`

A foreach statement looks like the following. Note the placement of parentheses, spaces, and braces.

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

5.6. `try`, `catch`

A try catch block 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
}

6. Closures

Closures MUST be declared with a space after the function keyword, and a space before and after the use keyword.

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
);

7. 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.

Apêndice A. Pesquisa

In writing this style guide, the group took a survey of member projects to determine common practices. The survey is retained herein for posterity.

A.1. Dados de Pesquisa

url,http://www.horde.org/apps/horde/docs/CODING_STANDARDS,http://pear.php.net/manual/en/standards.php,http://solarphp.com/manual/appendix-standards.style,http://framework.zend.com/manual/en/coding-standard.html,http://symfony.com/doc/2.0/contributing/code/standards.html,http://www.ppi.io/docs/coding-standards.html,https://github.com/ezsystems/ezp-next/wiki/codingstandards,http://book.cakephp.org/2.0/en/contributing/cakephp-coding-conventions.html,https://github.com/UnionOfRAD/lithium/wiki/Spec%3A-Coding,http://drupal.org/coding-standards,http://code.google.com/p/sabredav/,http://area51.phpbb.com/docs/31x/coding-guidelines.html,https://docs.google.com/a/zikula.org/document/edit?authkey=CPCU0Us&hgd=1&id=1fcqb93Sn-hR9c0mkN6m_tyWnmEvoswKBtSc0tKkZmJA,http://www.chisimba.com,n/a,https://github.com/Respect/project-info/blob/master/coding-standards-sample.php,n/a,Object Calisthenics for PHP,http://doc.nette.org/en/coding-standard,http://flow3.typo3.org,https://github.com/propelorm/Propel2/wiki/Coding-Standards,http://developer.joomla.org/coding-standards.html
voting,yes,yes,yes,yes,yes,yes,yes,yes,yes,yes,yes,yes,yes,yes,yes,no,no,no,?,yes,no,yes
indent_type,4,4,4,4,4,tab,4,tab,tab,2,4,tab,4,4,4,4,4,4,tab,tab,4,tab
line_length_limit_soft,75,75,75,75,no,85,120,120,80,80,80,no,100,80,80,?,?,120,80,120,no,150
line_length_limit_hard,85,85,85,85,no,no,no,no,100,?,no,no,no,100,100,?,120,120,no,no,no,no
class_names,studly,studly,studly,studly,studly,studly,studly,studly,studly,studly,studly,lower_under,studly,lower,studly,studly,studly,studly,?,studly,studly,studly
class_brace_line,next,next,next,next,next,same,next,same,same,same,same,next,next,next,next,next,next,next,next,same,next,next
constant_names,upper,upper,upper,upper,upper,upper,upper,upper,upper,upper,upper,upper,upper,upper,upper,upper,upper,upper,upper,upper,upper,upper
true_false_null,lower,lower,lower,lower,lower,lower,lower,lower,lower,upper,lower,lower,lower,upper,lower,lower,lower,lower,lower,upper,lower,lower
method_names,camel,camel,camel,camel,camel,camel,camel,camel,camel,camel,camel,lower_under,camel,camel,camel,camel,camel,camel,camel,camel,camel,camel
method_brace_line,next,next,next,next,next,same,next,same,same,same,same,next,next,same,next,next,next,next,next,same,next,next
control_brace_line,same,same,same,same,same,same,next,same,same,same,same,next,same,same,next,same,same,same,same,same,same,next
control_space_after,yes,yes,yes,yes,yes,no,yes,yes,yes,yes,no,yes,yes,yes,yes,yes,yes,yes,yes,yes,yes,yes
always_use_control_braces,yes,yes,yes,yes,yes,yes,no,yes,yes,yes,no,yes,yes,yes,yes,no,yes,yes,yes,yes,yes,yes
else_elseif_line,same,same,same,same,same,same,next,same,same,next,same,next,same,next,next,same,same,same,same,same,same,next
case_break_indent_from_switch,0/1,0/1,0/1,1/2,1/2,1/2,1/2,1/1,1/1,1/2,1/2,1/1,1/2,1/2,1/2,1/2,1/2,1/2,0/1,1/1,1/2,1/2
function_space_after,no,no,no,no,no,no,no,no,no,no,no,no,no,no,no,no,no,no,no,no,no,no
closing_php_tag_required,no,no,no,no,no,no,no,no,yes,no,no,no,no,yes,no,no,no,no,no,yes,no,no
line_endings,LF,LF,LF,LF,LF,LF,LF,LF,?,LF,?,LF,LF,LF,LF,?,,LF,?,LF,LF,LF
static_or_visibility_first,static,?,static,either,either,either,visibility,visibility,visibility,either,static,either,?,visibility,?,?,either,either,visibility,visibility,static,?
control_space_parens,no,no,no,no,no,no,yes,no,no,no,no,no,no,yes,?,no,no,no,no,no,no,no
blank_line_after_php,no,no,no,no,yes,no,no,no,no,yes,yes,no,no,yes,?,yes,yes,no,yes,no,yes,no
class_method_control_brace,next/next/same,next/next/same,next/next/same,next/next/same,next/next/same,same/same/same,next/next/next,same/same/same,same/same/same,same/same/same,same/same/same,next/next/next,next/next/same,next/same/same,next/next/next,next/next/same,next/next/same,next/next/same,next/next/same,same/same/same,next/next/same,next/next/next

A.2. Survey Legend

indent_type: The type of indenting. tab = “Use a tab”, 2 or 4 = “number of spaces”

line_length_limit_soft: The “soft” line length limit, in characters. ? = not discernible or no response, no means no limit.

line_length_limit_hard: The “hard” line length limit, in characters. ? = not discernible or no response, no means no limit.

class_names: How classes are named. lower = lowercase only, lower_under = lowercase with underscore separators, studly = StudlyCase.

class_brace_line: Does the opening brace for a class go on the same line as the class keyword, or on the next line after it?

constant_names: How are class constants named? upper = Uppercase with underscore separators.

true_false_null: Are the true, false, and null keywords spelled as all lower case, or all upper case?

method_names: How are methods named? camel = camelCase, lower_under = lowercase with underscore separators.

method_brace_line: Does the opening brace for a method go on the same line as the method name, or on the next line?

control_brace_line: Does the opening brace for a control structure go on the same line, or on the next line?

control_space_after: Is there a space after the control structure keyword?

always_use_control_braces: Do control structures always use braces?

else_elseif_line: When using else or elseif, does it go on the same line as the previous closing brace, or does it go on the next line?

case_break_indent_from_switch: How many times are case and break indented from an opening switch statement?

function_space_after: Do function calls have a space after the function name and before the opening parenthesis?

closing_php_tag_required: In files containing only PHP, is the closing ?> tag required?

line_endings: What type of line ending is used?

static_or_visibility_first: When declaring a method, does static come first, or does the visibility come first?

control_space_parens: In a control structure expression, is there a space after the opening parenthesis and a space before the closing parenthesis? yes = if ( $expr ), no = if ($expr).

blank_line_after_php: Is there a blank line after the opening PHP tag?

class_method_control_brace: A summary of what line the opening braces go on for classes, methods, and control structures.

A.3. Survey Results

indent_type:
    tab: 7
    2: 1
    4: 14
line_length_limit_soft:
    ?: 2
    no: 3
    75: 4
    80: 6
    85: 1
    100: 1
    120: 4
    150: 1
line_length_limit_hard:
    ?: 2
    no: 11
    85: 4
    100: 3
    120: 2
class_names:
    ?: 1
    lower: 1
    lower_under: 1
    studly: 19
class_brace_line:
    next: 16
    same: 6
constant_names:
    upper: 22
true_false_null:
    lower: 19
    upper: 3
method_names:
    camel: 21
    lower_under: 1
method_brace_line:
    next: 15
    same: 7
control_brace_line:
    next: 4
    same: 18
control_space_after:
    no: 2
    yes: 20
always_use_control_braces:
    no: 3
    yes: 19
else_elseif_line:
    next: 6
    same: 16
case_break_indent_from_switch:
    0/1: 4
    1/1: 4
    1/2: 14
function_space_after:
    no: 22
closing_php_tag_required:
    no: 19
    yes: 3
line_endings:
    ?: 5
    LF: 17
static_or_visibility_first:
    ?: 5
    either: 7
    static: 4
    visibility: 6
control_space_parens:
    ?: 1
    no: 19
    yes: 2
blank_line_after_php:
    ?: 1
    no: 13
    yes: 8
class_method_control_brace:
    next/next/next: 4
    next/next/same: 11
    next/same/same: 1
    same/same/same: 6

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