RockLESS

Update 2022

The less module (https://github.com/ryancramerdesign/Less) got some updates that make RockLESS obsolete. Please use Ryan's Less module instead!

Support forum thread: https://processwire.com/talk/topic/20658-rockless-php-less-parsing-helper-module/

This is a helper module for parsing LESS and returning the resulting CSS file or content. It uses the wikimedia less parser. See the docs here: https://github.com/wikimedia/less.php

Beside the methods provided by RockLESS you can call any of the underlying methods of the less parser. You can retrieve an instance of the parser easily:

$less = $modules->get('RockLESS');
$options = []; // optional
$parser = $less->getParser($options);
$parser->parseFile( '/var/www/mysite/bootstrap.less', '/mysite/' );
$css = $parser->getCss();

Parsing LESS files

Parsing a single file can be done via $less->parse() or its alias $less->parseFile(). But you can also parse multiple LESS files into one single CSS file:

$less = $modules->get('RockLESS');
$dir = $config->paths->assets;
$options = []; // optional, see docs at saveCSS method
$css = $less->parseFiles([
  $dir."foo.less",
  $dir."bar.less",
], $options);

This will always return the parsed CSS content ready for writing it to a file or to an inline <style> tag. This method will ALWAYS parse the files you throw into it, no matter if anything has changed or not. If you want to cache the results you can use the saveCSS method:

$less = $modules->get('RockLESS');
$dir = $config->paths->assets;
$options = []; // optional
$css = $config->paths->templates . "main.css";
$result = $less->saveCSS($css, [
  $dir."foo.less",
  $dir."bar.less",
], $options);

The method will return a WireData object holding the path and the url of the generated CSS file and the parsed CSS content:

The options array can hold the following settings:

• parserOptions: Options for the less parser.
• monitorFiles: Array of files to monitor for changes.
• monitorDirs: Array of directories to monitor for changes.
• monitorDirDepth: Depth of directories to monitor for changes.

Example:

$less = $modules->get('RockLESS');
$dir = $config->paths->assets;
$css = $config->paths->templates . "main.css";
$result = $less->saveCSS($css, [
  $dir."foo.less",
  $dir."bar.less",
], [
  'parserOptions' => ['compress' => true],
  'monitorFiles' => [
    $config->paths->assets."included-by-foo.less",
    $config->paths->assets."included-by-bar.less",
  ],
  'monitorDirs' => $config->paths->templates,
  'monitorDirDepth' => 3, // default is 0
]);

Use LESS files in your modules

Using RockLESS it is very easy to write your module's styles as LESS and not CSS. RockLESS has a addToConfig() method that will automatically parse a LESS file and add it to the $config->styles array. The css file will only be generated when it does not exist or the less file has changed:

// in init() method
$url = $this->config->urls($this);
$file = $url.$this->className.".less";
$less = $this->modules->get('RockLESS'); /** @var RockLESS $less */
if($less) $less->addToConfig($file);
else $this->config->styles->add("$file.css");

Sending PHP data/variables to LESS

Sometimes you might need to send PHP variables to your LESS files. For example you could want to create a stylesheet based on some user input.

$less = $modules->get('RockLESS');
$less->vars = [
  'foo' => 'bar',
];
$css = $less->getCSS($config->paths->templates . 'less/theme.less')->cssUrl;
echo "<link rel='stylesheet' type='text/css' href='$css'>";