How Can I Execute PHP Functions Inside HEREDOC Strings?

Accessing PHP Functions within HEREDOC Strings

In PHP, the HEREDOC string syntax provides a convenient method for defining multi-line text blocks. However, including complex expressions or function calls within these strings requires careful handling.

Traditionally, enclosing function calls in curly braces within a HEREDOC string would not work:

$string = <<<HEREDOC
{testfunction()}
HEREDOC;

To overcome this limitation, a more elaborate approach is required, involving storing the function name in a variable and calling it dynamically:

$fn = 'testfunction';
$string = <<<HEREDOC
{$fn()}
HEREDOC;

However, this method is cumbersome and decreases code readability.

A simpler approach is to use a custom function to process the curly-braced portion of the HEREDOC string:

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

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

By passing the desired data into this function, any expression or function call can be evaluated and the result included in the HEREDOC string.

Additionally, consider using template engines like Twig or Smarty to handle complex data processing and output generation, which can provide a cleaner and more organized approach.

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