Drupal 6 hook examples

gistfile1.aw

 <?php
 /**
  * Implements hook_help().
  */
 function helloworld_help($path, $arg) {
    switch ($path) {
      // Main module help for the helloworld module.
      case 'admin/help#helloworld':
        return '<p>' . t('Say hello to the world.') . '</p>';
    }
 }

/**
 * Implements hook_user().
 */
function helloworld_user($op, &$edit, &$account, $category = NULL) {
  switch ($op) {
    case 'after_update':
      drupal_set_message(t('User object updated.'));
      break;
  }
}

/**
 * Implements hook_nodeapi().
 */
function helloworld_nodeapi(&$node, $op, $a3 = NULL, $a4 = NULL) {
  drupal_set_message('Node Op: ' . $op);
}

/**
 * Implements hook_comment().
 */
function helloworld_comment(&$a1, $op) {
  drupal_set_message('Comment Op: ' . $op);
}


/**
 * Implements hook_block().
 */
function helloworld_block($op = 'list', $delta = '', $edit = array()) {
  switch ($op) {
    case 'list':
      $blocks['helloworld'] = array(
        'info'       => t('Helloworld user block'),
      );

      $blocks['configurable-text'] = array(
        'info'       => t('Helloworld: configurable text string'),
      );
 
      return $blocks;

    case 'configure':
      $form = array();
      if ($delta == 'configurable-text') {
        $form['helloworld_example_string'] = array(
          '#type' => 'textfield',
          '#title' => t('Block contents'),
          '#size' => 60,
          '#description' => t('This string will appear in the example block.'),
          '#default_value' => variable_get('helloworld_example_string',  t('Some example content.')),
        );
      }
      return $form;

    case 'save':
      if ($delta == 'configurable-text') {
        variable_set('helloworld_example_string', $edit['helloworld_example_string']);
      }
      return;

    case 'view':
      switch ($delta) {
        case 'helloworld':
          $block['subject'] = t('Helloworld');
          $block['content'] = helloworld_block_contents($delta);
          break;

        case 'configurable-text':
          $block['subject'] = t('Title of configurable-text block');
          $block['content'] = helloworld_block_contents($delta);
          break;
      }
      return $block;
  }
}

/**
 * A block content function.
 */
function helloworld_block_contents($delta) {
  switch ($delta) {
    case 'helloworld':
      global $user;
      $username = $user->name;
      $output = t('hello !username', array('!username' => $username));
      return $output;

    case 'configurable-text':
      $output = variable_get('helloworld_example_string',  t('A default value.'));
      return $output;
  }
}

/**
 * Implements hook_perm().
 */
function helloworld_perm() {
  return array('muck about with worlds');
}

/**
 * Implements hook_menu().
 *
 * Registers our settings page with Drupal.
 */
function helloworld_menu() {
  $items = array();
  $items['admin/settings/helloworld'] = array(
    'title' => 'Helloworld settings',
    'description' => 'Settings for helloworld related activities.',
    'page callback' => 'helloworld_settings_page',
    'access arguments' => array('muck about with worlds'),
    'type' => MENU_NORMAL_ITEM,
  );
  return $items;
}

/**
 * An administrative form for our module.
 */
function helloworld_settings_page() {
  $form = array();
  $form['helloworld_worldcount'] = array(
    '#type' => 'textfield',
    '#value' => '42',
    '#title' => t('How many worlds do we want to say hello to?'),
    '#description' => t('This should probably be an integer value unless you want to say hello to half a world.'),
    '#weight' => '-1',
  );

  //return drupal_render($form);
  return drupal_render(system_settings_form($form));
}

/**
 * Implements hook_form_alter()
 */
function helloworld_form_alter(&$form, $form_state, $form_id) {
  switch ($form_id){
    case 'user_login_block':
      $form['name']['#description'] = t('Enter your name here');
      $form['pass']['#description'] = t('Enter your password here');
      $form['submit']['#value'] = t('Log me in now please :-)');
    break;
  }
}