Aaron Piotrowski has a new post to his site talking about a feature of the next major release of the PHP language (PHP 7) around error and exception handling: working with throwable exceptions and errors.
Handling fatal errors in the past has been next to impossible in PHP. A fatal error would not invoke the error handler set by set_error_handler() and would simply halt script execution.
In PHP 7, an exception will be thrown when a fatal and recoverable error (E_ERROR and E_RECOVERABLE_ERROR) occurs, rather than halting script execution. Fatal errors still exist for certain conditions, such as running out of memory, and still behave as before by immediately halting script execution. An uncaught exception will also continue to be a fatal error in PHP 7. This means if an exception thrown from an error that was fatal in PHP 5.x goes uncaught, it will still be a fatal error in PHP 7.
He goes on to talk about the new interface that both Fatals and Errors implement to make catching them possible in PHP7: Throwable. He provides an example of what the interface would look like in PHP code and how to catch them (a simple try/catch). He then gets into each of the types and looks at the error and exception types they cover including TypeError, ParseError and AssertionError. He also includes an interesting part at the end of the post showing you how to write your error/exception handling to work correctly with both PHP 5 and PHP 7 at the same time.