Update: After further discussions on the CB, it turns out that the OP wants to set the first option to the first alphanumeric value.

What follows is an explanation of what the original code is doing.

You probably want: 

$mech->set_visible([ option => qr/.+/ ]);
#                              ^^

[download]
What you have is the same as: 
$mech->set_visible([ option => ($_ =~ m/.+/) ]);

[download]
In other words, you are passing the result of matching qr/.+/ against $_ (and this likely is where the Use of uninitialized value warning is coming from), not the regular expression itself.

In reply to Re: Using regex to select an option with WWW::Mechanize by pc88mxer
in thread Using regex to select an option with WWW::Mechanize by Lawliet

Title:
Use:  <p> text here (a paragraph) </p>
and:  <code> code here </code>
to format your post, it's "PerlMonks-approved HTML":


  • Posts are HTML formatted. Put <p> </p> tags around your paragraphs. Put <code> </code> tags around your code and data!
  • Titles consisting of a single word are discouraged, and in most cases are disallowed outright.
  • Read Where should I post X? if you're not absolutely sure you're posting in the right place.
  • Please read these before you post! —
  • Posts may use any of the Perl Monks Approved HTML tags:
    a, abbr, b, big, blockquote, br, caption, center, col, colgroup, dd, del, details, div, dl, dt, em, font, h1, h2, h3, h4, h5, h6, hr, i, ins, li, ol, p, pre, readmore, small, span, spoiler, strike, strong, sub, summary, sup, table, tbody, td, tfoot, th, thead, tr, tt, u, ul, wbr
  • You may need to use entities for some characters, as follows. (Exception: Within code tags, you can put the characters literally.)
            For:     Use:
    & &amp;
    < &lt;
    > &gt;
    [ &#91;
    ] &#93;
  • Link using PerlMonks shortcuts! What shortcuts can I use for linking?
  • See Writeup Formatting Tips and other pages linked from there for more info.