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[Caml-list] exception handling questions
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Date: 2003-11-06 (09:50)
From: Dustin Sallings <dustin@s...>
Subject: Re: [Caml-list] exception handling questions

On Nov 6, 2003, at 1:02, Richard Jones wrote:

>> 	One thing that really seems to be missing from exception handling is
>> the ability to print a stack trace from an exception.  I realize
>> there's a flag on the ocamlrun to print stacks for uncaught 
>> exceptions,
>> but that's not exactly what I'm looking for.  I'd like to be able to
>> catch and exception, log it, and continue.
>> 	Similarly, is there a way to print an exception at least like the
>> toplevel does?  I can catch any type of exception with the appropriate
>> pattern, but I don't see how I can report it without expecting it.
> And while we're at it, printing out a full stack trace with function
> names and parameters.

	Yes, that would be nice, but I'm trying to not ask for too much.  :)  
As it is, I've got a function that can fail when processing large 
amounts of data and it's OK to lose one as long as I know why.  Right 
now, the only way to know why is to rethrow:

let should_process fn =
         (ends_with fn ".") && (is_new_enough fn) && (not (is_gzip fn))
     with x ->
         print_endline("Unknown error determining whether to process " ^ 
         raise x

	Example output:

Unknown error determining whether to process /tmp/x/passwd.
Fatal error: exception Sys_error("/tmp/x/passwd.: Permission denied")

	I'd be plenty happy to print out that message and continue, but in the 
meantime, I've gotta have it abort.

Dustin Sallings

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