How do you use define within a heredoc? For example:
define('PREFIX', '/holiday');
$body = <<<EOD
<img src="PREFIX/images/hello.png" /> // This doesn't work.
EOD;
See Question&Answers more detail:ostaken from the documentation regarding strings
DEFINE('PREFIX','/holiday');
$const = PREFIX;
echo <<<EOD
<img src="{$const}/images/hello.png" />
EOD;