Background: In the recent thread help with simplifying program, BillKSmith recommended the use of <Algorithm::Combinatorics>. This uses iterators to go through combinations of data. I love to write terse code so I ended up with (which I did not post in the original thread): 

use strict;
use warnings;
use Algorithm::Combinatorics qw(combinations);

my $rep = 5; # should be 100
my @data = 0..$rep;
my $iter = combinations( \@data, 4 );
while( my ( $z, $y, $x, $w ) = @{ $iter->next // last } ) {
  next unless $w-2*$x+$y or $x-2*$y+$z;
  print "$w, $x, $y, $z\n";
}

[download]

My question is about the // last part. I reads nicely like "next or last" but I am aware that this exit from the while loop makes while redundant. I might as well use goto or write 

while(1){
    my ( $z, $y, $x, $w ) = @{ $iter->next // last };
    ...
}

[download]

What do you think about this use of last here? Is it a nice short way of exiting the loop when the iterator becomes undef when exhausted or is this breaking too much of the loop's structure? Or are there even hidden dangers that I have not spotted?

In reply to Unconventional exit from while loop by hdb

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.