I don't know what value this is, but this behavior isn't limited to map. If you substitute your map line with 
foreach my $a (@$aref) { };

[download]
The same thing will occur. The only thing that comes to mind as far as why this would happen is that two things are happening in both cases.

1) You're derefrencing the scalar as an array.
2) You're using a function that can modify the contents of that array.

In your other example, @$aref isn't modifiable. I personally wouldn't consider this a bug in perl. If you're going to access a refrence as an array, why is there a problem if it is an array?

Rich

In reply to Re: side effects of map by rchiav
in thread side effects of map by gregorovius

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.