d8_cache.module

<?php

/**
 * @file
 * d8_cache.module
 */

// For hook_views_pre_views.
use Drupal\views\ViewExecutable;

// For hook_node_save.
use Drupal\Core\Cache\Cache;
use Drupal\node\NodeInterface;

/**
 * Implements hook_node_presave().
 *
 * Invalid cache tags for node lists.
 */
function d8_cache_node_presave(NodeInterface $node) {
  $cache_tag = 'node:type:' . $node->getType();
  Cache::invalidateTags([$cache_tag]);
}

/**
 * Implement hook_views_pre_view().
 *
 * Add the time in the header of our views.
 */
function d8_cache_views_pre_view(ViewExecutable $view, $display_id, array &$args) {

  $contenu = "Il est: " . date('H:i:s');

  if ($view->id() == 'test_pages' && $display_id === 'page_1') {
    $options = [
      'id' => 'area_text_custom',
      'table' => 'views',
      'field' => 'area_text_custom',
      'relationship' => 'none',
      'group_type' => 'none',
      'admin_label' => '',
      'empty' => TRUE,
      'tokenize' => FALSE,
      'content' => $contenu,
      'plugin_id' => 'text_custom',
    ];
    $view->setHandler('page_1', 'header', 'area_text_custom', $options);
  }

  if ($view->id() == 'test_articles_block' && $display_id === 'block_1') {
    $options = [
      'id' => 'area_text_custom',
      'table' => 'views',
      'field' => 'area_text_custom',
      'relationship' => 'none',
      'group_type' => 'none',
      'admin_label' => '',
      'empty' => TRUE,
      'tokenize' => FALSE,
      'content' => $contenu,
      'plugin_id' => 'text_custom',
    ];
    $view->setHandler('block_1', 'header', 'area_text_custom', $options);
  }
}