PHP Coding Standards

This page describes the coding standards for the MovLib project. The coding standards are based on the Drupal coding standards. If something isn’t covered here, please refer to the Drupal coding standards.

Indenting and Whitespace

• Use an indent of 2 spaces, with no tabs.
• Lines should not exceed 120 characters.
• Lines should have no trailing whitespace at the end.
• Files should be formatted with \n as the line ending (Unix line endings).
• All text files should end in a single newline (\n). This avoids the verbose "\ No newline at end of file" patch warning and makes patches easier to read since it's clearer what is being changed when lines are added to the end of a file.
• Array indentation and chained method calls are also indented with 2 spaces.

<?php

// Do not forget the comma at the end of each line, this helps to prevent mistakes.
$myarray = [
  'level1' => [
    'level2' => 'value',
  ],
];

// Similar to what you are used to do in e.g. jQuery.
$myObject
  ->method1()
  ->method2($param)
  ->method3($param, $param1, $param2)
;

?>

Capitalization

• Procedural functions and variables are written all lower-case and in snake_case. function proc_fn($first_param)
• Object-oriented methods and properties are written in camelCase. public function ooMethod()
• Namespaces and class names are written in CamelCase. class OoClass
• Constants are written all upper-case and in SNAKE_CASE. define('MY_CONSTANT')
• Language literals are written all lower-case. true, false or null

Operators

• All binary operators (operators that come between two values), such as +, -, =, !=, ==, >, etc. should have a space before and after the operator, for readability. For example, an assignment should be formatted as $foo = $bar; rather than $foo=$bar;.
• Unary operators (operators that operate on only one value), such as ++, should not have a space between the operator and the variable or number they are operating on. For example $i++;.

Casting

Put a space between the (type) and the $variable in a cast: $mynumber = (int) $mystring.

Control Structures

Control structures include if, for, while, switch, etc. Here is a sample if statement, since it is the most complicated of them:

<?php

// if description comment goes here.
if (condition1 || condition2) {
  action1;
}
// elseif description comment goes here.
elseif (condition3 && condition4) {
  action2;
}
// else description comment goes here.
else {
  defaultaction;
}

?>

Note: Don't use else if — always use elseif.

Control statements should have one space between the control keyword and opening parenthesis, to distinguish them from function calls.

Always use curly braces even in situations where they are technically optional. Having them increases readability and decreases the likelihood of logic errors being introduced when new lines are added.

For switch statements:

<?php

switch (condition) {
  // Case 1 description goes here.
  case 1:
    action1;
    break;

  // Case 2 description goes here.
  case 2:
    action2;
    break;

  // Default description goes here.
  default:
    defaultaction;
}

?>

For loop statements:

<?php

do {
  actions;
} while ($condition);

while ($condition) {
  actions;
}

for ($i = 0; $i < $max; ++$i) {
  actions;
}

foreach ($array as $delta => $value) {
  actions;
}

?>

Quotes

Generally single quotes are preferred and strings should be concatenated, while the dot has to be surrounded be a whitespace. But it is allowed to use double quotes if the string is very short, does not contain any escape sequences and only normal PHP variables are embedded. If in doubt, use single quotes.

<?php

// Preferred
return '<h1 id="page-title">' . $title . '</h1>';

// WRONG
return '<h1 id="page-title">'.$title.'</h1>';
return '<h1 id="page-title">'. $title .'</h1>';
return '<h1 id="page-title">' .$title. '</h1>';

// Okay, if: short and no escaping
return "<$var>";

// WRONG
return "<{$var}>";
return "<tag attr=\\"$var\\">";
return "<{$this->func()}>";
return "<{$_SERVER['ENV']}>";

?>

Paths

Our software is only built for Linux (specifically Debian) operating systems. All paths within the web application have to be written specifically for that.

/var/www/folder