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jazfresh at hotmail.com
11 years ago
Sometimes you want a single catch() to catch multiple types of Exception. In a language like Python, you can specify multiple types in a catch(), but in PHP you can only specify one. This can be annoying when you want handle many different Exceptions with the same catch() block.

However, you can replicate the functionality somewhat, because catch(<classname> $var) will match the given <classname> *or any of it's sub-classes*.

For example:

<?php
class DisplayException extends Exception {};
class
FileException extends Exception {};
class
AccessControl extends FileException {}; // Sub-class of FileException
class IOError extends FileException {}; // Sub-class of FileException

try {
  if(!
is_readable($somefile))
     throw new
IOError("File is not readable!");
  if(!
user_has_access_to_file($someuser, $somefile))
     throw new
AccessControl("Permission denied!");
  if(!
display_file($somefile))
     throw new
DisplayException("Couldn't display file!");

} catch (
FileException $e) {
 
// This block will catch FileException, AccessControl or IOError exceptions, but not Exceptions or DisplayExceptions.
 
echo "File error: ".$e->getMessage();
  exit(
1);
}
?>

Corollary: If you want to catch *any* exception, no matter what the type, just use "catch(Exception $var)", because all exceptions are sub-classes of the built-in Exception.

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