PHP Error Handlers

How it works

Use a narrowly scoped handler when integrating an API whose warning-based failure contract needs conversion. Restore the previous handler in finally so unrelated code is not affected. Some fatal/engine-level failures have different handling rules. Production diagnostics should retain useful non-secret context while public responses remain controlled; do not expose raw filesystem paths or credential-bearing connection messages.

Run it locally

Run this complete source locally with PHP 8.2 or newer. Save it using the filename shown and run the command below. PHP is not currently available in Bhylu’s browser playground. Apache and MySQL are not needed for an ordinary CLI example.

php -l error-handlers.php
php error-handlers.php

Download this source as a local PHP lab file. Keep lab files separate from the Bhylu project and production data.

Example

<?php
declare(strict_types=1);

set_error_handler(function(int $severity,string $message,string $file,int $line): never {
    throw new ErrorException($message,0,$severity,$file,$line);
});
try {
    trigger_error("Controlled lab warning",E_USER_WARNING);
} catch (ErrorException $error) {
    echo "Warning adapted at boundary\n";
} finally { restore_error_handler(); }

Expected result

Warning adapted at boundary

The deliberate fixture warning becomes an exception inside this scoped block. No real file failure or external service is needed to exercise the handler. Restoring the previous handler matters in a larger application where another library may have its own error-reporting expectations.