Developer Area/Coding guidelines

This page documents the coding conventions used by Mahara. Everything that ends up in the git repository (other than third-party code) should follow these standards.

You can also have a look at the Reviewer's manual to see what reviewers will look at when looking at code submissions.

Separate pages with more information:

• PHP Files
• JavaScript Files (or snippets)
• TPL Files (may change in future if move away from smarty, ie to twig)

Accessibility

Mahara should be accessible to anybody. We are aiming to follow the WCAG 2.1 AA principles. There are a areas that we identified that require changes to achieve that aim. New and changed code should always be written with accessibility principles and guidelines in mind rather than tagged on 'when there is time'. Writing code accessible from the start makes it better code and requires less refactoring later on.

The style guide, accessible via 'yourmaharadomain/theme/styleguide.php', gives useful basic information for a lot of style elements.

Since the field of accessibility is changing, certain elements may require updates over time. You can find more information on our 'Accessibility' page.

File Headers

All files must adhere to the BasicPHPFileTemplates. There are slightly different templates depending on whether the script is to be included or whether it is to be directly hit.

Closing php tags ?> should be omitted.

Whitespace

Required:

• Indentation is using four (4) spaces, not tabs.
• Line endings should be "Unix-style" (\n), not "Windows-style" (\r\n).
• Avoid extra whitespace at the end of modified lines.
• Avoid editing whitespaces unrelated to your specific code change, when submitting a patch. It makes reviewing the patch more difficult and add unnecessary noise to the change history.

Recommended:

• There is no requirement that the scripts are wrapped at 80 columns, however developers are asked to wrap long lines sensibly.

Language Constructs

if/while/for statements

There is one space after each language construct, and no spaces between brackets or parentheses and the arguments inside them, unless what is inside them becomes too long for one line, in which case a special format will be used.

Examples of what is good:

if (1 == 2) {
    die('omg');
}

while ($i < 3) {
    echo 'I am ' . $i;
}

for ($i = 0, $j = 7; $i < 34, $j != 3; $i++, $j--) {
    echo ($i * $j) . ' is a silly number';
}

// Note bracing style of else if/else clauses
// Also note: do not use elseif
if ($a == $b) {
    echo "a = b";
}
else if ($c == $d) {
    echo "c = d";
}
else {
    echo "e = ?";
}

// Ternary operator
$a = ($b == true) ? 'hello' : 'goodbye';
// When used with other things on each side in the same statement:
$a = 'foo' . (($b == true) ? 'hello' : 'goodbye') . 'bar';

// A complicated condition. Note location of condition,
// and location of ending bracket and brace.
// todo: what was the decision here regarding conditions on the "if (" line?
if (
    $sacrificedgoats == $availablegoats
    && ($dogs == $cats
    || 1 != 2)
    || ($yesterday >> $tomorrow == 4)
) {
    // Do stuff
}


Examples of what is bad:

if ( $a == $b )
{
    echo 'hi';
}

if($c == $d) {
    echo 'hi';
} else {
    echo 'bye';
}

if ($e==$f)
{
    echo 'hi';
}
else
{
    echo 'bye';
}


What should be never used:

// For a really short condition
if ($a == $b) $c = 1;



switch/case statements

"case" should use multiline formatting:

switch ($var) {
    case 1:
        a = 25;
        b = 100;
        break;
    default:
        a = 0;
        b = 0;
}

NOT

case 1: a = 25; b = 100; break;

Variables and Arrays

Variables should be named with no underscores, and no capital letters. This policy may become more lenient in future if variable names are discovered that are not easily readable without underscores.

Do not name variables as negatives where possible - always use positive names and logical inversion (!) where required.

Hungarian notation is forbidden.

Aligning = signs for variable assignment is up to the developer, although they should use common sense in such decisions.

Hardcoded binary data is not allowed for security reasons.

Hardcoded serialised data is not allowed for security reasons.

Good:

$found = false;
$ponies = 0;
$servername = $overkill;

// Only in relation to controlling for/while loops
for ($i = 10; $i > 5; $i--) {
    echo $i;
}

// Aligning = signs
$mine   = 0;
$yours  = 0;
$theirs = 0;

// Only if the number of elements to initialise is small.
$array = array(1 => 'hello');

// If large number of elements to initialise:
$array = array(
    1  => 'hello',
    2  => 'goodbye',
    10 => 'erm'
);


Bad:

// Negative name
$notfound = true;
// Underscores
$my_variable = '';
// Hungarian
$count_i = 6;
// Uppercase letters
$myFish = $yourFish;

$array = array(
                1 => 'hello',
                2 => 'goodbye',
                10 => 'erm'
              );


Binary Operators

Always have a space on each side:

echo 1 + 2;
if (1 == 2)
echo 'hello' . ' world';


|| and && will always be used for 'or' and 'and' respectively. Resolve priority collisions with extra parentheses as required.

Classes, Functions and Methods

Nameing

Classes should start with upper case character, then each word capitalized.

class ExampleWhizbang {
    // ...
}

Leave double empty line between classes blocks in the code.

Functions should not use camel case, and instead use underscores as word seperators

function do_something(){
    // ...
}

NOT

function doSomething() {
    // ...
}

Function name must start with a letter (no _ character before function name, unless you declare magic method where double underscore is used).

Leave single empty line between two function blocks and between function block and code if function is used in non-library file.

The built-in PHP class "stdClass" should be written with a lowercase s, uppercase C, because that is its actual name. Other capitalizations, such as "StdClass" will not cause an error because invocations of classnames and functions are case-insensitive in PHP. However, it is good style to use the same capitalization as the declaration of the class/function.

Constructors without arguments should be called with empty parentheses after them.

Good:

$a = new stdClass();
$b = new RssBlock();

Bad:

// stdClass written incorrectly
$a = new StdClass();

// no parentheses after constructor
$b = new RssBlock;

// lowercase user-created class
$c = new fancyblock();

Declaration:

/**
* PHPDoc comment describing the function
*
* Note how the default value has no spaces
*/
function foo($a, Class $b, $c='') {
    // source
    return $value;
}

class FooBar extends Bar {

    /**
     * PHPDoc for the field
     *
     * For this project, do not use doThis.
     */
    public function do_this($c, $d) {
        // source
    }

}


Calling:

$result = foo($bar, $baz);
$mine = $object->method($a, $b);



Javascript

All files must adhere to the BasicJSFileTemplates. Javascript files should roughly follow Crockford's code conventions.