From: Dave Thomas <Dave@...>
Date: 2002-09-17T01:44:16+09:00
Subject: Re: Why are parser tools rarely used in ruby?

"MikkelFJ" <mikkelfj-anti-spam@bigfoot.com> writes:

> Why is it that all the ruby source I find in the Ruby (windows)
> distribution has zillions of handwritten parsers: rexml xpath, rdoc,
> sgml-parser ?

The RDoc history went something like this:

I wanted to do RDoc for a long time, and was waiting for a parser in
Ruby that could parse Ruby fully. There were (if I remember correctly)
three options, but none could do the full parse (and do things like
keep comments associated with the correct nodes in the parse
tree). That situation may have changed now.

At the same time, I was driven to keep RDoc self contained. I dislike
downloading a simple package only to find I need to download the
latest option parsing library (because the author preferred it over the
installed one, and even though the author used no features that
weren't in the standard one), strscan (because those extra 10mS are
important), an XML library (ust because...) and so on.

So, I had a look at the irb Ruby parser, and it turned out to be
fairly simple to adapt. I've been slowly hacking it down and removing
extra features over time, but even its first incarnation worked well,
and worked in a couple of days.

So, speaking for me, I found no compelling reason to use a parser
generator for RDoc. If I were using Ruby to parse a more regular
language, I'd probably use one.


Cheers


Dave