Be careful, it isn't actually a regex; it is a string that will be compiled
to a regex. You can see one difference here:
#!/usr/bin/perl
use v5.20;
use warnings;
say "string matches:";
for my $s ("foo", "AfooZ") {
say "\t$s: ", $s =~ "\Afoo\Z" ? "true" : "false";
}
say "regex matches:";
for my $s ("foo", "AfooZ") {
say "\t$s: ", $s =~ /\Afoo\Z/ ? "true" : "false";
}
which outputs
Unrecognized escape \A passed through at t.pl line 8.
Unrecognized escape \Z passed through at t.pl line 8.
string matches:
foo: false
AfooZ: true
regex matches:
foo: true
AfooZ: false
To my knowledge, the only delimiters that do not require m or qr before
them are // and ??; however, they are not equivalent (and ?? must be m?? as
of Perl 5.22). The m?? operator only matches the first time it sees a
pattern and then will not match again until reset is called:
#!/usr/bin/perl
use v5.18;
use warnings;
for ("fo", "foo", "fooo", "foooo") {
my ($match) = ?(fo+)?;
say $match // "no match";
if (/fooo/) {
reset;
}
}
Which outputs
Use of ?PATTERN? without explicit operator is deprecated at t.pl line 7.
fo
no match
no match
foooo
On Thu, Feb 23, 2017 at 6:53 PM Andrew Solomon <and...@geekuni.com> wrote:
> Thanks Uri!
>
> On Thu, Feb 23, 2017 at 10:32 PM, Uri Guttman <u...@stemsystems.com> wrote:
>
> On 02/23/2017 05:19 PM, Andrew Solomon wrote:
>
> Running Perl 18.2 I was surprised to discover that I can use single and
> double quotes as regex delimiters without the 'm' operator.
>
> For example, instead of writing
>
> "/usr/bin/perl" =~ m"/perl"
>
> I can just write
>
> "/usr/bin/perl" =~ "/perl"
>
> Can anyone point me to the documentation indicating which delimiters don't
> need the 'm' operator?
>
>
> you actually are thinking in the wrong direction. the =~ operator causes
> its right side to always be a regex unless the s/// or m// or tr/// ops are
> seen there. you can even use an expression or sub call or anything on the
> right of =~ and it will be parsed as a regex (if no op is there as i just
> said).
>
> you can easily check this out with something simple like "/usr/bin/perl"
> =~ "/pe" . "rl".
>
> so it isn't the delimiters as you think but the =~ op itself that makes it
> a regex.
>
> uri
>
> --
> To unsubscribe, e-mail: beginners-unsubscr...@perl.org
> For additional commands, e-mail: beginners-h...@perl.org
> http://learn.perl.org/
>
>
>
>
>
> --
> Andrew Solomon
>
> Mentor@Geekuni http://geekuni.com/
> http://www.linkedin.com/in/asolomon
>
