From: "Sebastian Spaeth" <Sebastian@SSpaeth.de>
To: Carl Worth <cworth@cworth.org>,
	Notmuch development list <notmuch@notmuchmail.org>
Subject: Re: Unhandled Xapian exception
In-Reply-To: <87bpd8or04.fsf@yoom.home.cworth.org>
References: <87aasul8h7.fsf@SSpaeth.de> <87bpd8or04.fsf@yoom.home.cworth.org>
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Date: Mon, 26 Apr 2010 11:28:07 +0200
Message-ID: <87y6ga1s2g.fsf@SSpaeth.de>
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On 2010-04-24, Carl Worth wrote:
> On Fri, 23 Apr 2010 13:21:56 +0200, "Sebastian Spaeth" <Sebastian@SSpaeth.de> wrote:
> > I propose to try..catch this code block and rather than returning VOID
> > it could return NOTMUCH_STATUS_SUCCESS or NOTMUCH_XAPIAN_EXCEPTION.
> > Not sure how "notmuch_database_find_message" would notify the caller of
> > such an exception situation though. The only possible failure value is
> > NULL (which also means did not find such a message).

> And to support that, we would need a different scheme in the
> library. Basically to just document that all calls might throw an
> exception and then not catch and print anything. That would at least be
> much simpler in the library. Then the top-level "notmuch" application
> could just have a C++ wrapper for main() that would catch and print the
> exception message.

I think the python API would not be able to catch a C++ exception at the
library level. I think the proper fix would be to guard the high level
lib/* functions (our public API) and modify the API as needed to notify
us.

E.g for msg* = notmuch_database_find_message(id) (which I used to test
the existence of a message and where NULL can now also mean that someone
modified the database and which renders that test somewhat useless), I
would propose that we make it:

NOTMUCH_STATUS status = notmuch_database_find_message(id, msg*)

where *msg will be filled with the message if it exists and xapian
exceptions are notified through the status code.

Does this make sense?

Sebastian