Thu, 2010-07-01 at 10:47 -0700, Andrei Alexandrescu wrote:
I think it
would be a good improvement to add such structure to
exceptions. So
toString() would continue to print essentially the same
message, but it
would assemble it from the separately-available
properties file, line,
and reason.
Go for it, or submit a ticket so it's not
forgotten.
Andrei
Lars Tandle Kyllingstad
wrote:
The library user would still get the information,
because
Throwable.toString() would still give the file and line
number, and like
I said, Throwable.file and Throwable.line are
supposed to be filled with
that information. My point was
that enforce() puts the information in
Throwable.msg, which I find
completely redundant.
Also, if you are using plain
enforce() for error checking (like Phobos
does in a lot of places),
Throwable.msg is your only source of
information to pass to the
user, since enforce() by default throws an
Exception and not an
InsightfulInformationException.
-Lars
On Thu, 2010-07-01 at 07:00 -0700,
Steve Schveighoffer wrote:
I disagree. The "user" in this
case, is the user of the library code. He does in fact need to know the
file/line that caused the problem, and more useful would be the full stack trace
so he can see where his code used the offending value.
If you are relying on enforce to give insightful error messages to an
actual user (that is, someone who runs your program), then you need some
training in user interface design :)
-Steve
-----
Original Message ----
From: Lars Tandle Kyllingstad <
ymailto="mailto:[email protected]";
href="mailto:[email protected]";>[email protected]>
To: Phobos mailing list <
href="mailto:[email protected]";>[email protected]>
Sent: Thu, July 1, 2010 9:50:15 AM
Subject:
[phobos] enforce() improvement
Often,
at least in small programs, when an exception is thrown you just
want
to present a sensible message to the user
and abort the
current
operation.
Example:
void
doStuff(int i) { enforce(i >= 0, "Need nonnegative i");
}
try
doStuff(-1);
catch
(Exception e) writeln("Error: ", e.msg);
In this
case, the user will
see
Error: b.d(5): Need nonnegative
i
My point is that the user doesn't need to see the file and line
number
that caused the error. This
is only useful for the
programmer. So I
suggest we make either of the following changes to
enforce():
1. Drop the file
and line number from the
message. The
Throwable
class has dedicated
'file' and 'line' fields which we can
populate
with that
information without polluting the error
message.
2.
Another option is to include the file and line
only in
debug
builds.
-Lars
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