WP 2.6 user defined constant Plugin conflict

The upcoming WordPress 2.6 introduces new user defined constant for specific critical system directory settings. This new improvement may seem like a small “change” but on plugin developer context it can be an impending disaster.

wp-config & wp-load files

Most plugin depend on “absolute path” to wordpress system file (wp-config.php). So the problem is there.

Lester-chan (GaMerZ) has this to say regarding the new WordPress 2.6 constant change.

The constant only get loaded when you load WP. Plugins will have problem finding wp-config.php or wp-blog-header.php from the plugin file.

might be broken in WP 2.6

require_once('../../../wp-config.php');

Long story, short

Below is my workaround for quick plugin activation setup. Its not the best solution as it involved the dirty “write-permission”, it need improvement. If you intent to uses it, there is few preliminary step to be set first:- ↓

1. browse to your plugin dir
2. create a blank php file: constant.php
3. copy paste the below code save it as new file relative to the constant.php
4. create or set your .htaccess and add Options All -Indexes.

Custom wp config file

function my_plugin_write_config()
{
	$constant = get_defined_constants(true);
	$user_defined = $constant['user'];
	unset($constant);

	$constant = array();

	// assuming that all latest wordpress CONSTANT start with WP_
	$wp_constant_prefix = "/WP_/";

	foreach($user_defined as $k=>$v){
		if (preg_match($wp_constant_prefix,$k)){
			$constant[$k] = $v;
		}
	}

	unset($user_defined);

	$constant['ABSPATH'] = (strtr(realpath(ABSPATH), array("\\", DIRECTORY_SEPERATOR)));
	$constant['WPINC'] 	= WPINC;
	$constant['WP_VERSION'] = get_bloginfo('version');

	$constant = array_map('json_encode',$constant);

	$my_plugin_config_file 	= dirname(__FILE__).DIRECTORY_SEPARATOR.'constant.php';

	if (is_writeable($my_plugin_config_file))
	{
		$content = "<?php if(!defined('MY_PLUGIN_TOKEN')) die('42');\n";

		foreach($constant as $k=>$v){
			$content .= sprintf('define(\'CONST_%1s\', %2s);',strtoupper($k),$v)."\n";
		}

		unset($constant,$k,$v);

		$content .= "?>";	

		$fp = false;

		if ( ($fp = fopen($my_plugin_config_file,'w+') ) != false) {
			stream_set_blocking($fp, TRUE);
			stream_set_timeout($fp,5);
			stream_set_write_buffer($fp, 0);
			fwrite($fp, $content);
			fclose($fp);
		}		

		unset($content,$my_plugin_config_file,$fp);

	} else {
		add_action('admin_notices','my_plugin_notification');
	}
}

function my_plugin_notification()
{
?>	<div id="message" class="error">
	<h3><?php _e('ERR') ?> </h3>
		<p><a href="http://doc.myplugin.com"><? _e('RTFM!'); ?></a></p>
	</div>
<?php
}

register_activation_hook(__FILE__, 'my_plugin_write_config' );
add_action('update_option_siteurl','my_plugin_write_config');
add_action('update_option_home','my_plugin_write_config');

Basically this script will search all user defined constant that start with “WP_” prefix, plus additional wordpress constant. Then it will write all these constant to disk inside “constant.php” (once). It also runs after a WordPress option has been update (active when user update settings for home & siteurl, I add the extra action hook just for example).

Deprecated Functions

Out of all this issue I still think WordPress as one of the best “back-compat friendly” CMS. Most of the legacy functions & variables (since version 0.71 >= 2.5) is still available inside WordPress system (wp-includes/deprecated.php). Not sure how long it will stay there..

Might be interested

• What You Need To Know About WordPress 2.6
• 10 Things You Need to Know About WordPress 2.6
• What Plugin Coders Must Know About WordPress 2.6