Dear monks,

I was reading the manual entry for glob the other day, and discovered a feature I hadn't used before: brace-only "wildcard" expressions can be used to generate strings with no globbing behaviour (that is, no matching against filenames in the current directory). The manual gives one example: 

@many =  glob "{apple,tomato,cherry}={green,yellow,red}";

[download]

It's closely related to the Perl 6 "X" operator, but limited to string elements only.

It's fun to try different ways to generate all pairs, triples or tuples of some length. For example, the following prints the coordinates of the standard chessboard: 

perl -E '$" = ","; my @pos = 'a'..'h'; say for <{@pos}{@{[ 1..@pos ]}}
+>'

[download]

Other than toy examples, have you used this kind of a glob in production code? What kind of non-trivial use cases can you suggest?

In reply to Actual use cases for non-filename behaviour of glob? by vrk

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.