Re: Perl, etc has these "?"-prefix modifiers/codes/whatever. Precisely which does emacs have (and NOT have)?

[pjb@informatimago.com (Pascal J. Bourguignon)]

John Withers <grayarea@reddagger.org> writes:

> On Thu, 2010-02-18 at 12:46 +0100, Pascal J. Bourguignon wrote:
>> dkcombs@panix.com (David Combs) writes:
>> 
>> > Subj:  Perl, etc has these "?"-prefix modifiers/codes/whatever.  
>> >        Precisely which does emacs have (and NOT have)?
>> >
>> >
>> > Please, someone, make an ascii or html table or even plain text 
>> > list of all these neat "new" non-standard ops that perl and
>> > even php and ruby etc seem to have now, comparing them
>> > to what Emacs has or don't have.
>> 
>> emacs lisp has a lot of data types.  But in lisp, the types are not
>> associated to the variables, but to the values.  Therefore names
>> (symbols are used to name things in general in lisp) don't need to be
>> marked in any special way.
>
> No, what he wants is for someone to go through and make a list of all
> the perl lookahead/behind assertions for regular expressions, even
> though the data is very easily found with a single google search and
> comes down to pretty much if it has a (?<symbol> then emacs doesn't have
> it, because the regexes in emacs haven't been touched since the
> neolithic.
>
> And finally he is looking for a code patch or pointers to where to look
> for something like this patch you can find with a simple google search:
> http://emacsbugs.donarmstrong.com/cgi/bugreport.cgi?msg=1;bug=5393
>
> And while I am more than happy to take digs at the lack of basic google
> searches and lazyweb requests, I do get the sentiment. At this point the
> entire rest of the world has moved on to perl-style regular expressions
> a good decade ago, and unlike many things about the world moving in a
> different direction than emacs, in this case they have more
> functionality. Lookahead and lookbehind assertions are useful. 

Ah, I thought he meant the $x @x #x whatever...

In the case of "regular expressions", when you add certain extensions,
they're not regular expressions at all, so, I will just cite Jamie
Zawinski:


    Some people, when confronted with a problem, think "I know, I'll use
    regular expressions."  Now they have two problems. 



-- 
__Pascal Bourguignon__