Jan Štětina

This plugin provides a simple API for storing miscellaneous log entries and their overview in admin area (or network 
admin area, if activated on a multisite).
Developed for private use (heavily used by my other plugins), but has perspective for more extensive usage. I can’t guarantee any support in the future nor further development, but it is to be expected. Kindly inform me about bugs, if you find any, or propose new features: <a href="mailto:zaantar@zaantar.eu?subject=[wordpress-logging-service]" rel="nofollow ugc">zaantar@zaantar.eu</a>.
See Usage and FAQ for more information.
<h3>API</h3>
Definitions:
<pre><code>WLS
</code></pre>
<ul>
<li>
should be checked before using any wls function
WLS_VERSION
</li>
<li>
should(!) contain current WLS version string
</li>
<li>
severity levels:
<pre><code>WLS_NOCATEGORY = 0

WLS_INFO = 1

WLS_NOTICE = 2

WLS_WARNING = 3

WLS_ERROR = 4

WLS_FATALERROR = 5
</code></pre>
</li>
</ul>
Functions:
<pre><code>wls_is_registered( $category_name );
</code></pre>
<ul>
<li>
returns <code>true</code>, if <code>$category_name</code> is registered
wls_register( $category_name, $description );
</li>
<li>
registers <code>$category_name</code> as a log category.
</li>
<li>
<code>$description</code> will be shown in admin area
wls_clear( $category_name );
</li>
<li>
deletes all log entries of category $category_name
wls_unregister( $category_name );
</li>
<li>
same as wls_clear & removes category $category_name from the list
wls_log( $category_name, $text, $user_id, $date, $blog_id, $severity = 0 );
</li>
<li>
inserts a new log entry into specified category
</li>
<li><code>$date</code> must be formated according to ISO 8601</li>
<li>
<code>$severity</code> should be one of defined severity levels (see above)
wls_simple_log( $log_name, $text, $severity = 0 );
</li>
<li>
equivalent to <code>wls_log( $category_name, $text, get_current_user_id(), date( 'c' ), get_current_blog_id(), $severity);</code>
</li>
</ul>

WordPress Logging Service

Provides a simple API for storing miscellaneous log entries and their overview in admin area.

chandima

Display log messages from PHP in the browser console in Safari, Firefox (with firebug), and Opera (with the new Dragonfly debugging environment). Essential debugging tool for 
plugin and theme developers. You no longer have to use ‘print_r’ statements from PHP to figure out what is going 
on in the code, which more often than not, messes up the DOM and HTML layout. Displays complex PHP structures like arrays and objects 
in pretty print.
Features
<ul>
<li>Log debug messages directly from themes and plugins.</li>
<li>Display log messages in the browser console, without muddying up the browser display.</li>
<li>Displays complex structures such as arrays and objects in pretty print.</li>
<li>Shows the line number and file from where the message was logged ( you won’t lose track of log statements ).</li>
</ul>
For more info, comments, and feature requests, visit <a href="http://www.turingtarpit.com/2009/05/wplogger" title="Wordpress Logger" rel="nofollow ugc">the plugin homepage</a>.
<h3>Credits</h3>
Code that forces the wplogger plugin to load first was adapted from the WordPress 
<a href="http://inchoo.net/wordpress/wordpress-firephp-plugin/" title="FirePHP plugin" rel="nofollow ugc">FirePHP plugin</a> 
developed by Ivan Weiller.
This plugin is based on <a href="http://pear.php.net/package/Log" title="PEAR Log" rel="nofollow ugc">PEAR Log</a>, the logging framework that is part of the 
PHP PEAR library. Current maintainers Jon Parise, Jan Schneider, and Chuck Hagenbuch. PEAR Log is based on code first 
developed for the Horde 1.3 framework – original authors Chuck Hagenbuch, and Jon Parise.
<h3>Release Notes</h3>
0.3 : Added support for Opera ;
0.2.2 : Fixed formatting issues in readme.txt file;
0.2.1 : Added more detail to the readme.txt file;
0.2 : First official public release;
0.1 : First internal release;

WordPress Logger

Display log messages during plugin and theme development on the console in Safari and Firefox (with Firebug) browsers.

WordPress Logging Service vs WordPress Logger