From: Ryan Davis <ryand-ruby@...>
Date: 2011-12-27T18:10:54+09:00
Subject: Re: Kernel#exit raises an exception?


On Dec 27, 2011, at 00:21 , Khat Harr wrote:

> I'm catching the exception code that is returned from ruby_exec_node() 
> in order to print out errors.  This is necessary in order to produce 
> error information because the implementation does not have console 
> window and allows end-users to add scripts.  'p' and 'print' are handled 
> by message boxes and if ruby_exec_node() returns an error code then the 
> implementation gathers $!.message and $!.backtrace and pops up a message 
> box describing the error.  There needs to be a way for the end users to 
> be informed of errors created by their scripts.  If I don't create a 
> handler for exit then the end-users won't be able to use 'exit' in their 
> scripts without producing an 'error' message box.


How will catching NoMemoryError, SignalException, or SystemExit help you? As I said, catching Exception is almost always a mistake. It certainly is in this case.

+ Exception
	+ NoMemoryError
	+ ScriptError
		+ LoadError
		+ NotImplementedError
		+ SyntaxError
	+ SignalException
		+ Interrupt
	+ StandardError (default for rescue)
		+ ArgumentError
		+ IOError
			+ EOFError
		+ IndexError
		+ LocalJumpError
		+ NameError
			+ NoMethodError
		+ RangeError
			+ FloatDomainError
		+ RegexpError
		+ RuntimeError (default for raise)
		+ SecurityError
		+ SystemCallError
			+ Errno::*
		+ SystemStackError
		+ ThreadError
		+ TypeError
		+ ZeroDivisionError
	+ SystemExit
	+ fatal