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

[Paolo Bonzini]

On 09/01/2010 03:45 PM, Jim Meyering wrote:
> > > > 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
>
> It's done for grep.
> I see no need to change any formal grammar.

Do you honestly imagine 
http://opengroup.org/onlinepubs/007908775/xbd/re.html changed to say "If 
a bracket expression consists of a colon, a series of alphabetic 
characters, and another colon, the implementation's behavior is undefined?

> > > 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?
>
> "We have nothing to fear but fear itself".
> But I doubt you're seriously worried about [A-Z], etc.

Not worried, but it honestly would be a sensible warning whenever 
strcoll ("A", "f") <= 0 && strcoll ("f", "Z") <= 0, as is the case in 
UTF-8 locales with glibc.  It will basically never do the right thing, 
since [A-Z] and [a-z] exclude a and Z respectively.

Paolo