Change record status: 
Project: 
Introduced in branch: 
8.x
Introduced in version: 
8.x
Description: 

The signature of hook_help() has changed to use route names instead of paths. The special route name help.page.[module_short_name] is used for the main module page. The current RouteMatch object is also passed in to hook_help() implementations, if more complex logic is needed.

Example - D7:

<?php
function dblog_help($path, $arg) {
  switch (
$path) {
    case
'admin/help#dblog':
     
$output = '';
     
$output .= '<h3>' . t('About') . '</h3>';
     
$output .= '<p>' . t('The Database logging module logs system events in the Drupal database. For more information, see the online handbook entry for the <a href="@dblog">Database logging module</a>.', array('@dblog' => 'http://drupal.org/documentation/modules/dblog')) . '</p>';
     
$output .= '<h3>' . t('Uses') . '</h3>';
     
$output .= '<dl>';
...
      return
$output;
    case
'admin/reports/dblog':
      return
'<p>' . t('The Database logging module monitors your website, capturing system events in a log (shown here) to be reviewed by an authorized individual at a later time. This log is a list of recorded events containing usage data, performance data, errors, warnings and operational information. It is vital to check the Recent log messages report on a regular basis, as it is often the only way to tell what is going on.') . '</p>';
  }
?>

Example, D8:

<?php
use Drupal\Core\Routing\RouteMatchInterface;
...
function
dblog_help($route_name, RouteMatchInterface $route_match) {
  switch (
$route_name) {
    case
'help.page.dblog':
     
$output = '';
     
$output .= '<h3>' . t('About') . '</h3>';
     
$output .= '<p>' . t('The Database Logging module logs system events in the Drupal database. For more information, see the online handbook entry for the <a href="!dblog">Database Logging module</a>.', array('!dblog' => 'http://drupal.org/documentation/modules/dblog')) . '</p>';
     
$output .= '<h3>' . t('Uses') . '</h3>';
...
      return
$output;

    case
'dblog.overview':
      return
'<p>' . t('The Database Logging module monitors your website, capturing system events in a log (shown here) to be reviewed by an authorized individual at a later time. This log is a list of recorded events containing usage data, performance data, errors, warnings and operational information. It is vital to check the Recent log messages report on a regular basis, as it is often the only way to tell what is going on.') . '</p>';
  }
}
?>

Note: add a use for RouteMatchInterface if it is not already there.

Impacts: 
Module developers
Updates Done (doc team, etc.)
Online documentation: 
Not done
Theming guide: 
Not done
Module developer documentation: 
Not done
Examples project: 
Not done
Coder Review: 
Not done
Coder Upgrade: 
Not done
Other: 
Other updates done