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List:       kde-core-devel
Subject:    Re: Memory Usage in KDE (LONG)
From:       Lars Knoll <Lars.Knoll () mpi-hd ! mpg ! de>
Date:       1999-10-18 16:08:50
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Hi,

On Mon, 18 Oct 1999, Waldo Bastian wrote:
[lots of interesting statistics about memory usage of exceptions deleted]

> * The overhead of exception handling is huge.
> * Qt and KDE should be compiled without support for exception handling.
> * The use of exceptions is depreciated.
> * Applications or libraries which need exception handling should enable
> it for themselves and make sure not to throw any exceptions to code
> which does not support it, including Qt. (Take expecially care of
> signals/slots and virtual functions)

These numbers are really interesting. I agree with you, that the memory
usage is huge. However, I don't like disabling exception handling in the
libs for one reason. People _will_ write software using exceptions and qt,
if we want them to or not. If we disable exception handling in the
libraries, they will run into trouble, because of Qt's signals/slots. With
them it is easily possible, that the programmer throws an exception in a
function called from the signal in the library. I think, the last point in
your list above is almost impossible to fullfill. If you do event based
programming in Qt, perhpas 80% of your code will be called from signals,
and thus from within the Qt library.

And I have problems removing exceptions from khtml, because the DOM
standard requires them. One could perhaps work around it using return
codes, but it would make the code and API really ugly und IMO almost
unusuable.

Also, I don't really understand, why exception handling should need such
huge, unshared data segments. Have you thought about talking to the egcs
guys about this problem? 

Cheers,
Lars

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