PHP callback just before script dies

Question

I have a set of custom PHP scripts. They load a main PHP file (to include other files, set settings, etc.) From this script I'd like to insert a callback function that is called by the scripts that included the main file just before ending.

What I intend to do is make a simple custom output cache with ob_get_contents(). I want to do ob_start() in main.php, then have the callback function store the output.

Answer 1

See register_shutdown_function:

Register a function for execution on shutdown

Example from the manual:

<?php
function shutdown()
{
    // This is our shutdown function, in 
    // here we can do any last operations
    // before the script is complete.

    echo 'Script executed with success', PHP_EOL;
}

register_shutdown_function('shutdown');
?>

Answer 2

ob_start() can do what you want:

ob_start('store_output');

function store_output($output) {
  // do something with $output
  return $output;
}

When the output buffer is flushed, the function will be called. Output buffers can be nested.