Calling PHP functions within HEREDOC strings

Question

In PHP, the HEREDOC string declarations are really useful for outputting a block of html. You can have it parse in variables just by prefixing them with $, but for more complicated syntax (like $var[2][3]), you have to put your expression inside {} braces.

In PHP 5, it is possible to actually make function calls within {} braces inside a HEREDOC string, but you have to go through a bit of work. The function name itself has to be stored in a variable, and you have to call it like it is a dynamically-named function. For example:

$fn = 'testfunction';
function testfunction() { return 'ok'; }
$string = <<< heredoc
plain text and now a function: {$fn()}
heredoc;

As you can see, this is a bit more messy than just:

$string = <<< heredoc
plain text and now a function: {testfunction()}
heredoc;

There are other ways besides the first code example, such as breaking out of the HEREDOC to call the function, or reversing the issue and doing something like:

?>
<!-- directly output html and only breaking into php for the function -->
plain text and now a function: <?PHP print testfunction(); ?>

The latter has the disadvantage that the output is directly put into the output stream (unless I'm using output buffering), which might not be what I want.

So, the essence of my question is: is there a more elegant way to approach this?

Edit based on responses: It certainly does seem like some kind of template engine would make my life much easier, but it would require me basically invert my usual PHP style. Not that that's a bad thing, but it explains my inertia.. I'm up for figuring out ways to make life easier though, so I'm looking into templates now.

Answer 1

If you really want to do this but a bit simpler than using a class you can use:

function fn($data) {
  return $data;
}
$fn = 'fn';

$my_string = <<<EOT
Number of seconds since the Unix Epoch: {$fn(time())}
EOT;