Assuming you're not hanging on to old versions of Perl, I'd write it as: 
given ($_) {
    when (/filename\s*=\s*(\S+)/) {$file = basename($1)}
    when (/go/ && exists $files{$file}) {
        push @PLACE, @batch;
        delete $files{$file}
}
@batch = ();

[download]
If it's in a for loop, and $_ is your loop variant, you can even omit the given.
Thing is, I think I understand what is happening here but not why: essentially, the call to basename() is not finding a good value in $1, which should have been returned from the match by the (\S+).
But you're not matching. qr// creates a pattern, it does not perform a match. qr/filename\s*=\s*(\S+)/ is always true. If you want to match, use m// instead.

In reply to Re: Climbing Mt. Perlcritic -- Switch statements by JavaFan
in thread Climbing Mt. Perlcritic -- Switch statements by chexmix

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.