A small MODX snippet to extract POST, GET, SESSION & COOKIE values - (c) 2012 ackwa.fr

argv.php

<?php
/*
 * A small MODX snippet to extract POST, GET, SESSION & COOKIE values - (c) 2012 ackwa.fr 
 *
 * @version : 1.0.1
 * @see     : https://gist.github.com/gists/2853625
 *
 * @usage   : [[!argv?key=`myparam`&default=`1`]]          -> return the value
 *            [[!argv?key=`myparam`&default=`1`&toph=`1`]] -> set [[+argv.myparam]]
 *            [[!argv?key=`myparam`&from=`GP`]]            -> return the value from GET or POST
 *
 * @history : 31/05/12 - 1.0.0 - Initial revision
 *            31/08/12 - 1.0.1 - Add a source(s) priority parameter (default PGSC)
 */
$sDefault = ((isset($default) && $default) ? $default :     '');
$sKey     = ((isset($key)     && $key)     ? $key     :     '');
$bPHolder = ((isset($toph)    && $toph)    ? true     :  false);
$sFrom    = ((isset($from)    && $from)    ? $from    : 'PGSC');

/*
 * Data sources
 */
$lSources = array('P' => '_POST', 'G' => '_GET', 'S' => '_SESSION', 'C' => '_COOKIE');

/*
 * Test requested key
 */
if ($sKey) {
    $sValue = $sDefault;
    foreach(str_split($sFrom) as $sSource) {
        if (isset($GLOBALS[$lSources[$sSource]][$sKey])) {
            $sValue = $GLOBALS[$lSources[$sSource]][$sKey];
            break;
        }   
    }
}
else {
    $sValue = $sDefault;
}

/*
 * Test output mode : return value or set placeholder
 */
if ($bPHolder) {
    $modx->toPlaceholder($sKey, $sValue, 'argv');
    $sValue = '';
}

return $sValue;