OpenEuphoria

Re: Try/Catch

• Posted by DerekParnell (admin) Jan 07, 2015
• 5843 views

Setting aside, for the moment, the examination of any compelling reasons to implement this concept into the language, I suggest a much more simpler approach - maybe a more Euphoric approach I think.

• A new procedure (let's call it 'trap_ex' for now) that takes one parameter - either the name of a routine, or a routine_id. This procedure registers an exception handler. The handler (the routine it identifies) would be a function that gets control when the run time Euphoria (back-end) calls RTFatal(). These would always be non-recoverable exceptions, meaning that after the handler has finished, the application will be terminated. Control does not return to the application.
• Make RTFatal() callable from user written code. This effectively implements the 'throw' concept.
• Routines that have been registered by trap_ex() will be added to a chain of such routines. RTFatal() will call each in reverse order of registration until the first of these functions return a non-zero integer. Then any further routines in the chain are not called and the application terminates immediately.
• A new procedure (let's call it 'untrap_ex' for now) that takes one parameter - either the name of a routine, or a routine_id. This procedure deregisters an exception handler. The handler (the routine it identifies) is removed from the RTFatal() call chain.
• RTFatal() should be enhanced to provide better exception data to the registered handlers.