On Mar 14, 2007, at 4:59 PM, Stuart Brorson wrote:
* One purported benefit for XML files is that there are lots of
open-source parsers for them available, making integration into
libgeda trivial. That's the theory, but in reality the job
of a parser is to parse the input, and then stick it into
datastructures suitable for use with the rest of gschem's code. An
open-source parser does about 1/3 of the job we need (i.e. reading the
file & creating some kind of parse tree). The rest of the job
involves putting the stuff in the parse tree into libgeda's data
structures. That's lots of work. Therefore, the purported advantage
of the freely-available XML parser is a chimera. Yes, it may be of
interest for a new program written from the ground up, but not for an
existing program like gEDA.
This is a very real point, and one that I can speak to from
experience. A few years ago, I converted a big-ish commercial
software product that I wrote from using a homebrew config file
parsing system (its config files are large) using lex/yacc and a
custom format to using XML with libxml2. Now I no longer have to
worry about fiddling with the lexer or the parser when I need to add
something, but it was a LOT of work to sprinkle the libxml2-parsed
data into my code's internal data structures.
In the end, while admittedly it's nice to not have to fiddle with
the lexer/parser code anymore when I add things to the file format,
I'm not sure if it was actually worth the effort. If I'd had a
better idea of the amount of effort it required beforehand, I likely
would not have done it.
-Dave
--
Dave McGuire
Port Charlotte, FL
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