~/perl/monks$ cat foo.txt
sub{"fish $_[0]"};


##</code><code>##

$foo_from_file = do "foo.txt";
foo("This is test 1\n", qr/test (.*)/, $foo_from_file);

sub foo { (my $text = $_[0]) =~ s/$_[1]/$_[2]->($1)/e;
          print $text; }