yes, this is a nasty one indeed. as we all know, Perl is case sensitive, but the Windows filesystem not. what happens here is that Perl stores information about the modules it has loaded in its %INC hash, and it ends up having two entries for Subclass1. if you add these lines at the end of the bla.pl script: 
use Data::Dumper;
print Dumper(\%INC);

[download]
you'll see something like: 
$VAR1 = {
          [...]
          'subclass1.pm' => 'subclass1.pm',
          [...]
          'Subclass1.pm' => 'Subclass1.pm',
          [...]
        };

[download]
so, the file is one but Perl sees (and loads) two modules. this could also pose serious problems with imported symbols, because when the case of the package name doesn't match, Perl loads the .pm file but doesn't export anything, as in: 
use fIlE::SpEc qw(catfile); # note the wrong case

$x = File::Spec->catfile('a', 'b', 'c'); # this works
$x = catfile('a', 'b', 'c'); # this croaks

[download]
this is even more unobvious, because the error goes unnoticed until you try to use something that's exported from the module.

unfortunately, Perl can't possibly catch this sort of errors, so you have to watch your case. one possible solution (for the typo-prone individuals :-) could be to always cut & paste the use line from the SYNOPSIS found in the module documentation.

cheers,
Aldo

King of Laziness, Wizard of Impatience, Lord of Hubris

In reply to Re: Windows pitfall: Subroutine redefined with use Modul by dada
in thread Windows pitfall: Subroutine redefined with use Modul by Brutha

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.