Hi Alan,
I asked the same question more than a few times years ago, and never
got an answer that was applicable to every situation. I finally realized
that this was because every error is different and there's no real
systematic way of dealing with them! The best I can offer is to make sure
you first find out where the error is. I never used MadExcept so I don't
know what kind of information it gives you. I've had the most success
tracking them down by having the Jedi JCL installed. It provides an option
that appears under Delphi's Project menu that you turn on called Jcl Debug
Info and automatically sets your project options up to provide the correct
information. Then turn your MAP file on to detailed, which is under the
Linker section of your Project options, and add the JvDebugHandler component
I and another guy first wrote together for Delphi 6. I've kept it updated
and it still works even with D2007. It can be found under the JvSystem Tool
Palette.
Turn all its properties on and then double-click it's OnOtherDestination
event and add code as below:
procedure TMainF1.JvDebugHandler1OtherDestination(Sender: TObject);
begin
JvDebugHandler1.ExceptionStringList.SaveToFile(IncludeTrailingPathDelimiter(
AppPath) + 'Exception Log.txt');
end;
In about 90% of the cases this has not only given me the exact line
on which the error occurred but also provides clues to its cause, as it
traces thru each event leading up to it. Just make sure you turn this
option off, get rid of the event and the component, and check your Linker
options again before making the final compile!
In the few instances where I am still unable to figure it out, I
usually put a breakpoint on a line in the Delphi editor, ( click in the left
margin ), somewhere before the error occurs and then run the app from the
IDE. When it stops at the break, I then move thru the rest of the app line
by line using Step Over, ( f8), until I again hit the error. And if that
doesn't clue me in, then I do the same but move thru it using Trace Into, (
f7 ), because this will take me thru the source as well and many times
that's where the culprit is! And if it is, sometimes youcan find another
way to do the samething, or at least find out if the problem is coming up
because you need to use it differently due to version differences. A nice
thing about using breakpoints too is that you can check the value of
variables anywhere preceeding the break by moving the mouse over them. HTH
from Robert Meek dba "Tangentals Design"
e-mail: [EMAIL PROTECTED]
Freelance Windows Programming for XP and Vista
Also proud to be a Moderator of the "Delphi-List" at elists.org
"Reality cannot be explained...only enjoyed or endured as your current
perspective allows!"
Hi folks --
As someone who's still a relative newbie, I'm having a difficult time
understanding the bugs in an application I wrote. The part that seems so
strange to me is that they only happen on Windows XP. I get the same errors
on different XP machines, while getting no errors when I try the application
on either Vista or Windows 2000. I installed a copy of madExcept to try
learning more but some of the report info is a bit beyond my abilities to be
helpful.
Happily, the problems do fall into repeatable patterns. In one case the
culprit seems to be the @LStrClr function in Delphi (2006's) System unit.
This produces the kind of access violation you get when a method is
referencing memory set to 00000000. In the other case, the
TCustomClientDataSet.RecNo method calls TCustomClientDataSet.Check and
creates a DBClient exception with the message "at end of table."
Beside the fact that I don't know much about Delphi's source code, the other
thing that makes these problems hard for me is that they don't happen on my
development machine (which is running Vista)--I cannot recreate them.
Although I would be thrilled to receive whatever specific advice you'd care
to give, I would also be curious about general advice re: how to handle
errors that you can't reproduce. They must be common for anyone who has a
fairly sizable user base.
Thanks, as always -- Al C.
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