A couple of simple functions to help with debugging ClassicPress plugins in development.

debug.php

<?php

// Prevent direct access.
if (strpos($_SERVER['PHP_SELF'], 'debug.php')) {
	die();
}

/**
 * Debug - to expose data in variables, arrays, objects.
 * 
 * @author John Alarcon
 *
 * @param mixed 	$var 	Required. The variable, array, object to debug.
 * @param boolean 	$name	Optional. Add a name for the item being debugged.
 * @param integer 	$pad 	Optional. Move debug display to the right by this many pixels.
 * @param boolean 	$exit 	Optional. Stop script execution.
 */
function debug($var, $name=false, $pad=0, $exit=false) {
	$prefix = 'codepotent-debug-mixed';
	$unique = rand(123456, 456789);
	echo "\n\n";
	echo '<style>';
	echo 'div.'.$prefix.'-container-'.$unique.' {clear:both;margin:25px 0 0 !important;padding:0 !important;}';
	echo 'div.'.$prefix.'-container-'.$unique.' pre.'.$prefix.'-code {overflow-x:scroll;margin:0 0 0 '.(int)$pad.'px !important;padding:10px !important;border:1px solid #ccc;background:#f2f2f2;font-family:monospace;font-size:11pt;line-height:1.25em !important;}';
	echo 'div.'.$prefix.'-container-'.$unique.' h2.'.$prefix.'-heading {font-size:11pt;padding:0 !important;margin:0 !important;}';
	echo 'div.'.$prefix.'-container-'.$unique.' .'.$prefix.'-red-text {color:#f00;}';
	echo '</style>'."\n";
	echo '<div class="'.$prefix.'-container-'.$unique.'">'."\n";
	echo '<pre class="'.$prefix.'-code">'."\n";
	echo '<h2 class="'.$prefix.'-heading '.$prefix.'-red-text">'.(($name)?'$'.$name.' ['.gettype($var).']':gettype($var)).'</h2>'."\n";
	print_r($var)."\n";
	if ($exit) {
		echo '<br />&lt;-----[ <strong class="'.$prefix.'-red-text">script terminated</strong> ]-----&gt;'."\n";
	}
	echo '	</pre>'."\n";
	echo '</div>'."\n";
	echo "\n\n";
	if ($exit) {
		die();
	}
}

/**
 * Debug - to expose data in single, basic variables.
 * 
 * A lightweight function to expose data within basic variables; best used in loops.
 * 
 * @author John Alarcon
 *
 * @param mixed 	$var 	Required. The variable to debug.
 * @param boolean 	$name 	Optional. Add a name for the item being debugged.
 * @param integer 	$pad 	Optional. Move debug display to the right by this many pixels.
 * @param boolean 	$exit	Optional. Stop script execution.
 */
function line($var, $name=false, $pad=0, $exit=false) {
	$prefix = 'codepotent-debug-line';
	$unique = rand(123456, 456789);
	echo "\n\n";
	echo '<style>';
	echo 'div.'.$prefix.'-container-'.$unique.' {clear:both;margin:0 !important;padding:0 !important;font-family:monospace !important;'.(($pad!==0)?'margin-left:'.(int)$pad.'px !important;' : '').'}';
	echo 'div.'.$prefix.'-container-'.$unique.' span {font-size:11pt;}';
	echo 'div.'.$prefix.'-container-'.$unique.' .'.$prefix.'-red-text {color:#f00;}';
	echo 'div.'.$prefix.'-container-'.$unique.' .'.$prefix.'-black-text {color:#000;}';
	echo 'div.'.$prefix.'-container-'.$unique.' .'.$prefix.'-gray-text {color:#999;}';
	echo '</style>'."\n";
	echo '<div class="'.$prefix.'-container-'.$unique.'">'."\n";
	echo '<span class="'.$prefix.'-black-text"><strong>&gt;</strong></span> ';
	if ($name) {
		echo '<span class="'.$prefix.'-red-text"><strong>$'.$name.'</strong></span> <span class="'.$prefix.'-gray-text">=</span> ';
	}
	echo '<span class="'.$prefix.'-black-text">'.$var.' <span class="'.$prefix.'-gray-text">['.gettype($var).']</span></span>';
	if ($exit) {
		echo '<br />> &lt;-----[ <strong class="'.$prefix.'-red-text">script terminated</strong> ]-----&gt;'."\n";
	}
	echo '</div>'."\n";
	echo "\n\n";
	if ($exit) {
		die();
	}
}