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List:       koffice-devel
Subject:    Re: design discussion: caching QTextFormat for faster text loading
From:       zander () kde ! org
Date:       2010-08-17 13:13:22
Message-ID: 201008171513.22460.zander () kde ! org
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On Tuesday 17. August 2010 10.07.01 Jos van den Oever wrote:
> > Notice that your assertion of many formats is not true; please write some
> > test code to convince yourself :)
> 
> If you are so sure, you should be able to explain it.

I guess I can; it would be nice of you to put some time into the 
investigations when I ask you to; I'm trying to help you in your efforts by 
mentoring you as much as I can. You writing some code is in line with that.

> > So I agree its the fastest to implement since it continues the current
> > approach and just adds a cache on top.
> 
> It adds many caches on top in a place where it does not belong.
> 
> > As a besides I suggest you should take a little more care to not call the
> > stuff I wrote 'uninsightful' without checking your facts. Either way, its
> > not nice.
> 
> I did not write that you mail was uninsightful, i wrote that the manner in 
> which styles are handled is uninsightful. 

Which is code I wrote and designed ;)

> > Use my suggestion of a QMap doing this and connect to the QTextDocument
> > destroyed signal to flush cache and you have a cache per document.
> 
> This is very, very ugly. The style classes have no business knowing what 
> document they belong to or worse, when that document is loaded or
> unloaded,  let alone via an opaque mechanism like signals and slots. 

As I wrote before; don't see it as a document, see it as a key the size of a 
void*

> They
> should be concerned with holding style properties and converting them to
> QTextFormat objects and that is all. By mixing in other concepts the code
> becomes cluttered and hard to maintain.

There is no such mixing if you don't get confused by the idea that the unique 
key for a format includes a QTextDocument pointer.

> > >  - minimizes the sizes of all QTextFormat instances by placing as much
> > > style  information in parent object (e.g. QTextFrame).
> > Not needed; there is a minimum amount of them already.
> 
> You say that again, but I'm not convinced. What do you consider minimum? I 
> would consider having only one QTextObject minimum. Is this also the case
> in  KPresenter?

Talk is cheap; you don't accept my assertions, then write the 3 lines of code 
to prove it either way. :-)
Here it is; http://pastebin.com/W17snq3s

-- 
Thomas Zander
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