Perl正则表达式(使用一个变量作为包含Perl操作符字符的搜索字符串)

$text_to_search = "example text with [foo] and more";
$search_string = "[foo]";

if ($text_to_search =~ m/$search_string/)
    print "wee";
$text_to_search = "example text with [foo] and