Re: [perl #109798] '/e' regexp modifier is not recognized by re pragma

On Mon, Feb 6, 2012 at 5:42 AM, demerphq <demerphq@gmail.com> wrote:

> On 5 February 2012 23:12, Eric Brine <ikegami@adaelis.com> wrote:
> > On Sun, Feb 5, 2012 at 12:22 PM, demerphq <demerphq@gmail.com> wrote:
> >>
> >> On 5 February 2012 01:19, Eric Brine via RT <perlbug-followup@perl.org>
> >> wrote:
> >> > On Sat Feb 04 16:15:49 2012, ikegami@adaelis.com wrote:
> >> >> On Sat Feb 04 04:05:02 2012, glitchmr@myopera.com wrote:
> >> >> > When '/e' modifier is used with 're' module, Perl complains about
> >> >> > unknown modifier. Personally, I think that informing about '/e'
> >> >> > not being able to be used by 're' module would be more useful.
> >> >> >
> >> >> >     C:\Users\Konrad>perl -e "use re '/e'"
> >> >> >     Unknown regular expression flag "e" at -e line 1
> >> >>
> >> >> That message is accurate.
> >> >>
> >> >> >perl -e" /(?e:x)/ "
> >> >> Sequence (?e...) not recognized in regex; marked by <-- HERE in m/(?e
> >> >> <-- HERE :x)/ at -e line 1.
> >> >>
> >> >> "e" is not a regular expression flag. It is a substitution operator
> >> >> flag.
> >> >
> >> > Also note that "e" is not mentioned in perlre. The regex flags are (as
> >> > listed in perlre): m, s, i, x, p, g, c, a, d, l, u.
> >>
> >> Just to note, perlre does not decide this. regexp.h does.
> >>
> >> > (I find this very odd that p, g and c are regex flags instead of match
> >> > substitute operator flags, but they are are.)
> >>
> >> Huh?!
> >>
> >> /p relates to how we manage $`, $&, $', and has nothing to do with
> >> substitution.
> >>
> >> /g relates to how match
> >>
> >> /c relates to how we match.
> >>
> >> None of them have anything to do with substitution.
> >
> >
> > Perl disagrees.
>
> No it does not.
>
> I said "relates to how we match",


You said "Huh?!" when I said g, c and p are match and substitution operator
flag, not regex flags.

Perl gives errors when you use "g" and "c" as regex flags.

$ perl -e'qr/foo/c'
Having no space between pattern and following word is deprecated at -e line
1.
Bareword found where operator expected at -e line 1, near "qr/foo/c"
syntax error at -e line 1, near "qr/foo/c
"
Execution of -e aborted due to compilation errors.

$ perl -e'qr/foo/g'
Having no space between pattern and following word is deprecated at -e line
1.
Bareword found where operator expected at -e line 1, near "qr/foo/g"
syntax error at -e line 1, near "qr/foo/g
"
Execution of -e aborted due to compilation errors.

$ perl
-we'qr/(?g:foo)/'

Useless (?g) - use /g modifier in regex; marked by <-- HERE in m/(?g <--
HERE :foo)/ at -e line 1.

$ perl
-we'qr/(?c:foo)/'

Useless (?c) - use /gc modifier in regex; marked by <-- HERE in m/(?c <--
HERE :foo)/ at -e line 1.


$ perl -we'use re "/g";'
Unknown regular expression flag "g" at -e line 1


$ perl -we'use re
"/c";'

Unknown regular expression flag "c" at -e line 1

[It doesn't give errors for /p, though. but I don't see how that makes any
sense.)]

which means "the m// modifier". Not
> the qr// modifier. A qr// operator does not *match* anything. It
> *compiles* a pattern


Exactly. Since qr// doesn't actually match, only regex pattern flags can be
attached to it, which proves that "g" and "c" aren't regex flags. Contrary
to perlre.

- Eric

• [perl #109798] '/e' regexp modifier is not recognized by re pragma by GlitchMr
• [perl #109798] '/e' regexp modifier is not recognized by re pragma by Eric Brine via RT
• [perl #109798] '/e' regexp modifier is not recognized by re pragma by Eric Brine via RT
• Re: [perl #109798] '/e' regexp modifier is not recognized by re pragma by demerphq
• Re: [perl #109798] '/e' regexp modifier is not recognized by re pragma by Eric Brine
• Re: [perl #109798] '/e' regexp modifier is not recognized by re pragma by demerphq
• Re: [perl #109798] '/e' regexp modifier is not recognized by re pragma by Eric Brine
• Re: [perl #109798] '/e' regexp modifier is not recognized by re pragma by demerphq
• Re: [perl #109798] '/e' regexp modifier is not recognized by re pragma by Eric Brine
• Re: [perl #109798] '/e' regexp modifier is not recognized by re pragma by Brad Gilbert
• Re: [perl #109798] '/e' regexp modifier is not recognized by re pragma by Tom Christiansen
• Re: [perl #109798] '/e' regexp modifier is not recognized by re pragma by demerphq
• Re: [perl #109798] '/e' regexp modifier is not recognized by re pragma by Tom Christiansen
• Re: [perl #109798] '/e' regexp modifier is not recognized by re pragma by demerphq
• Re: [perl #109798] '/e' regexp modifier is not recognized by re pragma by Ronald J Kimball
• Re: [perl #109798] '/e' regexp modifier is not recognized by re pragma by demerphq
• Re: [perl #109798] '/e' regexp modifier is not recognized by re pragma by Tom Christiansen
• Re: [perl #109798] '/e' regexp modifier is not recognized by repragma by Paul Johnson
• Re: [perl #109798] '/e' regexp modifier is not recognized by re pragma by Tom Christiansen
• Re: [perl #109798] '/e' regexp modifier is not recognized by re pragma by Karl Williamson
• Re: [perl #109798] '/e' regexp modifier is not recognized by re pragma by Eric Brine
• Re: [perl #109798] '/e' regexp modifier is not recognized by re pragma by Tom Christiansen
• Re: [perl #109798] '/e' regexp modifier is not recognized by re pragma by demerphq
• Re: [perl #109798] '/e' regexp modifier is not recognized by re pragma by Tom Christiansen
• Re: [perl #109798] '/e' regexp modifier is not recognized by re pragma by demerphq
• Re: [perl #109798] '/e' regexp modifier is not recognized by re pragma by Tom Christiansen
• Re: [perl #109798] '/e' regexp modifier is not recognized by re pragma by demerphq
• Re: [perl #109798] '/e' regexp modifier is not recognized by re pragma by Eric Brine
• Re: [perl #109798] '/e' regexp modifier is not recognized by re pragma by demerphq
• [perl #109798] '/e' regexp modifier is not recognized by re pragma by James E Keenan via RT