function getModuleNames in Demonstration site (Sandbox / Snapshot) 8
To get module directories.
1 call to getModuleNames()
- demo_set_info in ./demo.module 
File
- ./demo.module, line 644 
Code
function getModuleNames() {
  $dirs = [];
  foreach (\Drupal::moduleHandler()
    ->getModuleList() as $module => $filename) {
    $dirs[$module] = $filename
      ->getExtensionFilename();
  }
  return $dirs;
}