Developer Area/Coding guidelines/PHP files

This page documents the coding conventions used by Mahara for PHP files. 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.

For other languages, use the links at the main guideline page.

The Basics

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.

Indentation is using four (4) spaces. There is no requirement that the scripts are wrapped at 80 columns, however developers are asked to wrap long lines sensibly.

Documenting Code

• Comments at the head of files, functions, classes, etc should use the /** ... */ comment form for compatibility with PHPDoc and JSDoc.
• Explanatory comments in the body of the code should use only // comment markers, regardless of the length of the comment.
  • This allows /* ... */ markers to be used for quick mass commenting during debugging.
• Comments about a line of code should be placed on their own line above that line of code, rather than at the end of it.
  • This makes them more visible to people scanning the page, and ensures they won't be hidden off the side of the page if the reader's editor window is small.

Example:

/**
 * First line is a summary of what this function does and can only be one line.
 *
 * More detail can be presented with a blank line between the summary
 * and description. This can be a multiline block.
 *
 * The description can also be multiple paragraphs.  The description ends with a
 * blank line if there are any @tags that follow.
 *
 * @param boolean $bar description of the purpose of $bar
 * @param string $baz description of the purpose of $baz
 * @param array $qux description of the purpose of $qux
 * @return array|string This function either returns $qux with $baz added to it, or $baz with $bar added to it
 */
function foo($bar, $baz='bax', $qux=array()) {
    
    // This part is difficult and requires a long
    // explanation. This is that explanation. I am
    // still typing to see if I can make it to four
    // lines.
    if ($bar) {
        // put it on the end
        $qux[] = $baz;
        return $qux;
    } else {
        // I'm sure this makes sense somehow
        return $baz || ((string) $bar);
    }
}

PHPDocumentor

Building local docs is simple enough. We recommend using the official Docker build at phpdoc/phpdoc.

Your experience with the actual documentation may vary. There has been a recent push this year (2021) to get the local documentation more fully complete.

Execute from the repo root to build the full documentation.

mkdir -p docs/complete;
docker run --rm -v ${PWD}:/data phpdoc/phpdoc  -d ./htdocs/ -t ./docs/complete

To build a subset:

mkdir -p docs/test;
docker run --rm -v ${PWD}:/data phpdoc/phpdoc  -f ./htdocs/path/to/directory/* -t ./docs/test

Language Constructs

Strings

Recommended:

• Strings should be quoted with single quotes (')
  • Unless you are interpolating a variable
  • Or writing a string with lots of single quotes in it.
• Variable interpolations should be written with {curly braces} around them.

Examples:

$a = 'This is a string.';
$b = "This's a string that's got lots of apostrophes (i.e. <b>'</b> characters), in it. Ain't it pretty nifty?";
$c = "My {$field} is {$users[$1]->$field}";

require/require_once/include/include_once

These statements should have brackets around the argument. There is no space between the statement and the bracket. In effect, this is the same as a function call.

require_once('my/file.php');

NOT:

require_once 'my/file.php';
require_once ('my/file.php');

Plugin files must be included using the safe_require() function. This function ensures that there are no vulnerabilities in accessing a plugin file. Plugins that do not use this function to include files should be considered vulnerable to a possible security vulnerability.

Any include statements in the core should never have a variable in their name, to reduce the chance of an arbitary include vulnerability.

The include path is set automatically to be the current directory plus the lib directory - there is no need to specify an absolute directory path.

if/while/for statements

There is one space after each language construct, and no spaces between brackets 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;

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.

When related variables are initialised, the = signs for them should line up. Other than that, aligning = signs for variable assignment is up to the developer, although they should use common sense in such decisions.

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. Eew....
$count_i = 6;
// Uppercase letters
$myFish = $yourFish;

// Not necessarily "bad", just not for this project
$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 brackets as required.

Functions and Methods

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);