[cad-linux-dev] text <-> binary
- From: Janek Kozicki <janek_listy@xxxxx>
- To: cad-linux-dev@xxxxxxxxxxxxx
- Date: Sat, 6 Dec 2003 01:41:48 +0100
cr88192 said: (by the date of Fri, 5 Dec 2003 16:00:35 -0800)
<snip>
> if one uses a b-tree style encoding, one can incrementally rewrite bits of
umm.. what is b-tree? possible that I know it, and it's just I don't
know this name...
> the file, and not need an explicit "save" operation (making large files a
> lot more practical). combined with a log, one can also have various manner
> of undo's.
if you use CVS or any other version management system you can have not
only undos but many different branches of undo, too. You can also mix
several different [undo] barches of a drawing into another drawing.
I am talking about text files stored in directories.
> but a problem comes up here:
> if a binary format is used (especially a b-tree+log) then the openness of
> the format is largely reduced...
>
> again: I am primarily considering use of a text based format (s-expressions,
> aka "lisp syntax").
> my planned approach is that geometry will likely be split into multiple
> files, though my cad is not taking this approach as of present (it is a bit
> too early in the development...).
have a look at:
http://www.catb.org/~esr/writings/taoup/html/ch01s06.html
there is also something wise written about binary data formats :)
<text - binary>
stream operations are less problematic than binary format operations.
what if you once decide that your drawing needs more precision (eg. from
float to long double)?
in text file you just have: 1.02340230023 and adding more digits to it will
not destroy anything. But adding more bytes into binary format, how would
you do it? rewrite whole file? what if you have already 3000 files with
obsolete format?
> misc:
> I did not recieve an email for this response.
> can someone indicate how I am supposed to respond on this list (or if the
> email is on some sort of delay...).
some problems with newsgroup? strange...
(I had to resend this message, hopefully it will not appear twice on the
list)
--
# Janek Kozicki
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