scanf style parsing

Tim Hammerquist tim at vegeta.ath.cx
Fri Sep 28 00:28:16 CEST 2001


Me parece que Skip Montanaro <skip at pobox.com> dijo:
> 
>     Tim> It's not usually easy to learn regexps, no matter what your
>     Tim> background.  I come from C/C++ roots (Turbo C++ 3.0) and TRS-80
>     Tim> BASIC before that, and I certainly had no idea what regex's were
>     Tim> really for until I looked at Perl.
> 
> I think the best way to learn about regular expressions is to use
> incremental regular expression searching in Emacs/XEmacs.  Just bind C-s and
> C-r to isearch-forward-regexp and isearch-backward-regexp.  Then, every time
> you search you're using re's.  Initially you'll just use plain strings, but
> eventually start mixing in "." and character classes.  Before you know it
> "*" and "+" will be your buddies too.  Once you start adding "\(", "\|" and
> "\)" to your repertoire, you will attain enlightenment. ;-)

I used Emacs briefly and couldn't get the hang of it; besides, vi's
command mode keys were just a bit more mnemonic for me.

> You'll generally never cook up complex regular rexpressions using
> incremental search because you have no convenient way to correct mistakes
> and retry, but you will use all the pieces and build up more complex stuff
> when you're programming Perl or Python.  Making the leap from Emacs's
> old-style re's to POSIX-style re's as Perl and Python use now is fairly
> straightforward.  Mostly it involves getting rid of backslashes and learning
> about {m,n}, \d, \s and other little shortcuts.  (I still almost never use
> \d.  My fingers just type [0-9] automatically.)

All true.

> maybe-the-best-argument-against-vi-ly, yr's

This I don't understand.  Where was the argument against vi? vi (at
least vim) uses regex's for it's search; it just uses '/' and '?'
instead of the C-s/C-r mapping you mentioned.  It is also a good way for
Perler's to get used to "old-style" re syntax (ie, the one with a lot of
backslashes). <wink>

Cheers,
Tim
-- 
The two surviving chocolate people copulate desperately, losing
themselves in a melting frenzy of lust, spending the last of their
brief, borrowed lives in a spasm of raspberry cream and fear.
    -- Narrator, The Sandman



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