Calling PHP functions within HEREDOC strings

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;

I would not use HEREDOC at all for this, personally. It just doesn't make for a good "template building" system. All your HTML is locked down in a string which has several disadvantages

  • No option for WYSIWYG
  • No code completion for HTML from IDEs
  • Output (HTML) locked to logic files
  • You end up having to use hacks like what you're trying to do now to achieve more complex templating, such as looping

Get a basic template engine, or just use PHP with includes - it's why the language has the <?php and ?> delimiters.

template_file.php

<html>
<head>
  <title><?php echo $page_title; ?></title>
</head>
<body>
  <?php echo getPageContent(); ?>
</body>

index.php

<?php

$page_title = "This is a simple demo";

function getPageContent() {
    return '<p>Hello World!</p>';
}

include('template_file.php');