I am not a big fan of using the ref() function. So when I test to see if a reference is defined, I often use: 
if(defined @$arrayref && @$arrayref)
{
    # do something with @$arrayref like:
    for my $i (@$arrayref)
    {
          print $i;
    }

}

[download]
I have always been under the impression that this if construct prevents perl from dying if $arrayref is undefined or not an actual array reference. I came across some code today, however, that makes me question that belief. 
#!/usr/bin/perl

use strict;

my $arrayref = [];

if(defined @$arrayref)
{
    print "arrayref defined\n";

}
else
{
    my $ref = ref $arrayref;
    print "arrayref not defined ref=$ref\n";
}

[download]
This returns: "arrayref not defined ref=ARRAY" But if I change this line: 
my $arrayref = [];

[download]
to 
my $arrayref;

[download]
I get the same result. So the question is, does: if(defined @$arrayref) actually test for definition of the array reference in such a way that you could then perform operations on @$arrayref from within the block without crashing Perl?

In reply to Testing for definition of references by DBX

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.