Depends on where you data comes from. Provided you completely trust it you can do: 

@list = qw( this that other \w+\s\w+ );
$re = join '|', @list;
$re = qr/$re/;
print "Match\n" if 'foo bar' =~ m/$re/;

[download]

This is fine BUT if you have say '(foo' in your list it will crash as the unmatched ( is invalid. You can cure this with a quotemeta 

$re = join '|', map{quotemeta} @list;

[download]

The problem with this is that ALL regex metachars will get escaped so our '\w+\s\w+' in the previous example will get escaped to '\\w\+\\s\\w\+' which will loses its wildcard bahaviour and matches that literal string.

You could use eval to see if the RE compiles BUT that is potentially dangerous. Don't use string eval..... 

my $re;
my $str = '(foo';
eval {$re = qr/$str/};
if ( $@ ) {
    print "Oops $@\n";
}
print "Still running.....$re\n";

$str = '/;print"You hacked me!";/';
eval {$re = qr/$str/};
if ( $@ ) {
    print "Oops $@\n";
}
print "Still running.....$re\n";

$str = '/;print"You hacked me!\n";/';
eval "\$re = qr/$str/";
if ( $@ ) {
    print "Oops $@\n";
}
print "Still running.....$re\n";
__DATA__
Oops Unmatched ( before HERE mark in regex m/( << HERE foo/ at C:\PROG
+RA~1\PERLBU~1\debug\test.pl line 5.

Still running.....
Still running.....(?-xism:/;print"You hacked me!";/)
*****You hacked me!
Still running.....(?-xism:)

[download]

cheers

tachyon

s&&rsenoyhcatreve&&&s&n.+t&"$'$`$\"$\&"&ee&&y&srve&&d&&print

In reply to Re: Safe way to do regexp tests indirectly by tachyon
in thread Safe way to do regexp tests indirectly by AndyH

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