[Kst] QTextStream to QDomElement

[Andrew Walker]

Probably the best argument against it. However, it does
have the benefit of enforcing good practices. If we
had used QDomElement from the beginning it would
have given people a good reason to do this:

<plot x=2 y=4... / >

instead of

<plot>
	<x>2<x/>
	<y>2<y/>
	.
	.
	.
<plot/>

The kst files would all be half the size they are now. If we're
routinely posting 300kB kst files to ELOG then I would argue
that this matters.

Andrew

On Friday 14 January 2005 10:34, Barth Netterfield wrote:
> How about if we don't do it because it just doesn't matter?
>
> On January 14, 2005 01:25 pm, Andrew Walker wrote:
> > Okay, so this demonstrates that the Qt implementation of XML
> > is very slow compared to other implementations. It doesn't say
> > anything about how QDomElement compares to QTextStream
> > speed-wise though. Is it possible that QTextStream is just as bad?
> >
> > Andrew
> >
> > On Friday 14 January 2005 10:15, George Staikos wrote:
> > > On Friday 14 January 2005 12:56, Andrew Walker wrote:
> > > > The first may be true. Have you actually measured this for the
> > > > kind of files we are saving? The second point I disagree with.
> > > > We should not have to be worrying about indentation,
> > > > endl, closing tags, delimiters, etc that QTextStream compels
> > > > us to. I'll reserve judgment on your third point.
> > >
> > >    QDom is known to be very slow.
> > > http://xmlbench.sourceforge.net/results/benchmark200402/index.html
> > > I also saw some slides about this at a talk.
> > >
> > >    We are definitely dealing with big DOM documents too.  The ones in
> > > Paris were around 300kb (just the XML!!), and Nicolas uses .kst files
> > > even bigger than that.
> > >
> > >     There are future cases where we will also need to extract fragments
> > > of the DOM as text, so we will be even more wasteful there, creating a
> > > complicated heavyweight structure only to convert back to text, and
> > > then back to DOM again.
> > >
> > >     Finally, write out an example both ways and you'll see that it's
> > > much more tedious to write with QDom.  The indentation stuff is not
> > > necessary, but it was very easy to sneak in and makes it easier to deal
> > > with those files for debugging.
> > >
> > >    QDom is certainly more elegant than QTextStream, but it's not
> > > "ready" yet.
> > >
> > >    Note: QDom4 will be much faster than libxml even, apparently, so it
> > > might change things a bit.  That's probably 1.5-2 years into Kst's
> > > future though.
> >
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