> perl -we'use strict; use P;
my $re_str=qr{([0-6BS])};
$_="B";
my $ans;
if (eval m{$re_str}) {
  $ans=$1;
}
P "ans=%s, re_s=%s", $ans, $re_str;
'
ans=B, re_s=(?^:([0-6BS]))

##</code><code>##

my $re_str="qr{(&#91;0-6BS&#93;)}";
$_="B";
my $ans;
if (eval m{$re_str}) {
$ans=$1;
}
P "ans=%s, re_s=%s", $ans, $re_str;'

##</code><code>##

my $re_str="qr{(&#91;0-6BS&#93;)}";
$_="B";
my $ans;
if (eval P (q(my $re=%s; m{$re}), $re_str) ) {
$ans=$1;
}
P "ans=%s, re_s=%s", $ans, $re_str;'

##</code><code>##

my $re_str="qr{(&#91;0-6BS&#93;)}";
$_="B";
our @ans = m{$re_str};                                         
P "ans=%s, re_s=%s", \@ans, $re_str;'