PHP: Prevent nested try-catch from catching a specific error - php

Question

I have a PHP script which needs to execute a callback function and catch a specific type of error.
<?php
class MyException extends Exception{}
function doStuff(callable $callback){
try{
$callback();
}
catch(MyException $e){
#Deal with it
}
}
?>
The callback function can use a try-catch which will prevent my exception being bubbled up. How can I allow the callback function to implement try-catch blocks but not allow it to catch MyException?

Answer 1

Forgive me if I've read the question wrong - I can not think of a use case where this is required - but I think something like this will work:
<?php
class MyException extends Exception {}
/*
* This method is in the library. It's not in your control
*/
function doStuff(callable $callback) {
try {
$callback();
} catch(Exception $e) {
die($e->getMessage());
}
}
/*
* We want to do something, but not let any MyException pass through to doStuff()
*/
doStuff(function() {
try {
connect('mysql:dbname=IDoNotExist;host=127.0.0.1', 'batman', 'robin');
} catch(MyException $e) {
return; // Do nothing with MyException, continue as if it didn't happen
} catch(Exception $e) {
throw new Exception($e); // Not an instance of MyException ... let the library handle it
}
});
/*
* This is dummy code that will throw MyException if the username and password are incorrect
*/
function connect($dsn, $username, $password) {
try {
$dbh = new PDO($dsn, $username, $password);
} catch(PDOException $e) {
throw new MyException($e->getMessage());
}
}
I'm assuming, by reading the comments and your responses, that doStuff() is some library call that you pass a callable to. If the code inside your callback catches a MyException you want to completely ignore this.
The code above will completely ignore MyException as if nothing happened. Although I would never advocate such a solution.