Why isn't admin_notices displaying my text? [Simple Plugin, Beginner]

Question

Here is some code that is the result of four days of studying Wordpress and PHP. Unfortunately, it's not working the way it's supposed to. Nothing displays at the admin_notices bar.

Originally, I thought it was the $filename = is_plugin_active($filename) ? "$filename: Active" : "$filename: Disabled"; line, but that was not the problem. What say you?

function show_names()
{                  
  $paths = array();

  foreach (glob("*/plugins/*") as $filename) {                                                                                                          
    $filename = is_plugin_active($filename) ? "$filename: Active" : "$filename: Disabled";
    $filename = str_replace('wp-content/plugins/', '', $filename);
    $paths[] = $filename;   
    }

  $paths = implode("---", $paths);
  echo $paths;
}

add_action("admin_notices", "show_names");

Answer 1

var_dump($paths); shows that the your $paths variable is an empty string. It's not showing anything because there is nothing to show.

Since you seem like you're trying to find all the plugins, you should have a look at get_plugins. glob is going to be relative to the current working directory (with will vary depending on your server setup) and is_plugin_active active takes a plugin_basename.

get_plugins will return an associative array with the plugin basenames as keys as the file header data as the values (in an array).

A few other notes:

admin_notices does not automagically format your notices to look pretty. You can wrap it your notice with <div class="error"> or <div class="updated"> to do that.

Always give your functions a unique prefix or put them in a namespace (PHP 5.3+ only).

Revised code:

<?php
add_action('admin_notices', 'wpse72637_show_names');
function wpse72637_show_names()
{                  
    $paths = array();

    foreach(get_plugins() as $p_basename => $plugin)
    {
        $paths[] = "{$plugin['Name']}: " .
            (is_plugin_active($p_basename) ? 'Active' : 'Disabled');
    }

    echo '<div class="updated"><p>', implode(' --- ', $paths), '<p></div>';
}