"Intro to Pyparsing" Article at ONLamp

[Anton Vredegoor]

Paul McGuire wrote:

> I just published my first article on ONLamp, a beginner's walkthrough for
> pyparsing.
>
> Please check it out at
> http://www.onlamp.com/pub/a/python/2006/01/26/pyparsing.html, and be sure to
> post any questions or comments.

I like your article and pyparsing. But since you ask for comments I'll
give some. For unchanging datafile formats pyparsing seems to be OK.
But for highly volatile data like videotext pages or maybe some html
tables one often has the experience of failure after investing some
time in writing a grammar because the dataformats seem to change
between the times one uses the script. For example, I had this
experience when parsing chess games from videotext pages I grab from my
videotext enabled TV capture card. Maybe once or twice in a year
there's a chess page with games on videotext, but videotext chess
display format always changes slightly in the meantime so I have to
adapt my script. For such things I've switched back to 'hand' coding
because it seems to be more flexible.

(Or use a live internet connection to view the game instead of parsing
videotext, but that's a lot less fun, and I don't have internet in some
places.)

What I would like to see, in order to improve on this situation is a
graphical (tkinter) editor-highlighter in which it would be possible to
select blocks of text from an (example) page and 'name' this block of
text and select a grammar which it complies with, in order to assign a
role to it later. That would be the perfect companion to pyparsing.

At the moment I don't even know if such a thing would be feasible, or
how hard it would be to make it, but I remember having seen data
analyzing tools based on fixed column width data files, which is of
course in a whole other league of difficulty of programming, but at
least it gives some encouragement to the idea that it would be
possible.

Thank you for your ONLamp article and for making pyparsing available. I
had some fun experimenting with it and it gave me some insights in
parsing grammars.

Anton