Here is an exemple how to use the assertion callback function :
<?php
assert_options( ASSERT_CALLBACK, 'assert_callback');
function assert_callback( $script, $line, $message ) {
echo 'You have a design error in your script <b>', $script,'</b> : line <b>', $line,'</b> :<br />';
echo '<b>', ereg_replace( '^.*//\*', '', $message ), '</b><br /><br />';
echo 'Open the source file and check it, because it\'s not a normal behaviour !';
exit;
}
$x = 3;
assert('is_integer( $x ) && ($x >= 0) && ($x <= 10); //* $x must be an integer value from 0 to 10' );
echo "0 <= $x <= 10";
?>
assertion is usefull for "design by contract" methodology ...