gistfile1.aw

<?php
function escape_my_code( $attr, $content = null ) {
        $content = clean_pre($content); 
        return '<pre"><code>' .
                str_replace('<', '&lt;', $content) . 
                '</code></pre>';
    }
add_shortcode('code', 'escape_my_code');

?>

/*記事内で[code]<?php echo 'Hello World!' ?>[/code]と書く*/