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From: Eli Zaretskii <eliz@gnu.org>
To: Jim Blandy <jimb@codesourcery.com>
Cc: msnyder@specifix.com, gdb@sourceware.org
Subject: Re: Watchpoints with condition
Date: Tue, 04 Dec 2007 21:07:00 -0000	[thread overview]
Message-ID: <uhciyyxu2.fsf@gnu.org> (raw)
In-Reply-To: <m3zlwqfk5z.fsf@codesourcery.com> (message from Jim Blandy on 	Tue, 04 Dec 2007 09:23:52 -0800)

> Cc: Eli Zaretskii <eliz@gnu.org>,  gdb@sourceware.org
> From: Jim Blandy <jimb@codesourcery.com>
> Date: Tue, 04 Dec 2007 09:23:52 -0800
> 
> I guess I don't see why 'GDB stops your program whenever the value of
> this expression changes' is hard to understand.

Two reasons: (1) most people think watchpoints watch variables, not
expressions; and (2) the notion of "foo == 1" being an expression
whose value is either 1 or zero is natural only to C hackers.

> Explaining conditional watchpoints is a superset of explaining
> watchpoints, so I don't see how it could be simpler.

It is simpler because you still watch a simple variable, and the
condition is kept separately.  It is similar to

   x = y + (foo == 1);

vs

   if (foo == 1)
     x = y + 1;
   else
     x = y;

The latter shows what the code does more clearly (and in fact some
coding standards advise against the former style).

  parent reply	other threads:[~2007-12-04 21:07 UTC|newest]

Thread overview: 24+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2007-11-30 16:25 Vladimir Prus
2007-11-30 16:37 ` Daniel Jacobowitz
2007-11-30 21:16 ` Eli Zaretskii
2007-11-30 23:30   ` Jim Blandy
2007-11-30 23:49     ` Daniel Jacobowitz
2007-12-03 17:54       ` Jim Blandy
2007-12-03 18:11         ` Daniel Jacobowitz
2007-12-03 20:59         ` Eli Zaretskii
2007-12-03 23:07           ` Jim Blandy
2007-12-04  4:23             ` Eli Zaretskii
2007-12-04  5:11               ` Michael Snyder
2007-12-04 17:24                 ` Jim Blandy
2007-12-04 17:30                   ` Paul Koning
2007-12-04 21:07                   ` Eli Zaretskii [this message]
2007-12-04 23:17                   ` Michael Snyder
2007-12-05 21:37                     ` Jim Blandy
2007-12-01  1:10 ` Russell Shaw
2007-12-01  1:46   ` Michael Snyder
2007-12-01  9:16     ` Eli Zaretskii
2007-12-04  2:04 ` Michael Snyder
2007-12-04  7:25   ` Vladimir Prus
2007-12-04 10:48     ` Michael Snyder
2007-12-04 14:07       ` Daniel Jacobowitz
2007-12-04 21:08     ` Eli Zaretskii

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