Re: have you ever mistyped [[:lower:]] as [:lower:] ?

[Paolo Bonzini]

On 09/01/2010 02:51 PM, Jim Meyering wrote:
> Who knows... POSIX may allow this new behavior, someday.
> Wouldn't you adjust sed if POSIX were to permit special
> handling of obviously-erroneous regular expressions?

Permit, I don't know. Mandate, of course.  In any case, I don't want to 
lead the way.

> > It's a huge mistake, because making it an error means
> > changing the regex grammar (and making it unnecessarily complicated
> > and contrived).
>
> It's already done in grep, and wasn't a very big change.

You're conflating the formal grammar and the code that implements it. 
The latter is allowed to include this kind of "hack", the former cannot. 
 POSIX

> > I still think this is wrong, and doubly wrong because I cannot disable
> > it on my system without breaking it with POSIXLY_CORRECT.  Please,
>
> You want to disable it?
> I doubt you intend to use grep '[:space:]'...,
> so I still fail to understand why you would want that.

Just because I value the difference between "syntactic validation" 
(errors) and "semantic validation" (warnings).  Call me a purist. :)

> It sounds like you're upset.
> Sorry it's come to that, but I feel strongly about this, too.

I'm not upset, but I'm very much worried of making a mistake.  What if 
someone proposes to warn for [A-Z] and [a-z] whenever they're not going 
to do what the user thinks (they're not synonyms of any of [[:upper:]], 
[[:lower:]], [[:alpha:]])?  Are we going to make that an error?

Also, I'm trying to mediate though between our positions.  What's wrong 
with the alternative plan I outlined?  Actually I'm more upset because 
you didn't answer that part. :)

Paolo