Add (?^...) regex construct

This adds (?^...) to signify to use the default regex modifiers for the
cluster or embedded pattern-match modifier change.  The major purpose of
this is to simplify regex stringification, so that "^" is output in
place of "-xism".  As a result, the stringification will not change in
the future when new regex modifiers are added, so tests, etc. that rely
on a particular stringification will have to change now, but never
again.

Code that needs to work properly with both old- and new-style regexes
can use something like the following:

    # Accept both old and new-style stringification
    my $modifiers = (qr/foobar/ =~ /\Q(?^/) ? '^' : '-xism';

This construct is Ben Morrow's idea.

1 files changed, 1 insertions, 1 deletions

diff --git a/lib/Dumpvalue.t b/lib/Dumpvalue.t
index 8eb70a34b8..6570e38a2e 100644
--- a/lib/Dumpvalue.t
+++ b/lib/Dumpvalue.t
@@ -130,7 +130,7 @@ is( $out->read, '', 'unwrap ignored glob on first try');
 $d->unwrap(*FOO);
 is( $out->read, "*DUMPED_GLOB*\n", 'unwrap worked on glob');
 $d->unwrap(qr/foo(.+)/);
-is( $out->read, "-> qr/(?-xism:foo(.+))/\n", 'unwrap worked on Regexp' );
+is( $out->read, "-> qr/(?^:foo(.+))/\n", 'unwrap worked on Regexp' );
 $d->unwrap( sub {} );
 like( $out->read, qr/^-> &CODE/, 'unwrap worked on sub ref' );