Line 4 is still a lot of fanning-about, but it doesn't even compile

"@{[__LINE__}]" is a syntax error because you've swapped the } and ] - "@{[__LINE__]}" works fine.

some convenient token such as $LINE (or $__LINE__ or whatever I can just embed in double-quotes)

Nope, at least not built in, sorry. __LINE__ is like a function call, as of Perl 5.16 you can even write it as __LINE__().

Personally, I'd suggest living with the "fanning-about" or writing a helper function to output debug info (e.g. using caller). (Update: TIMTOWTDI - AnomalousMonk's printf suggestion is nice too. Personally, if it was a case where I didn't feel like it's worth it to write a helper, I'd probably write print "Line ",__LINE__,"\n";)

But since this is Perl, of course there's also a way to hack it:

use warnings;
use strict;

{
    package LineNumber;
    sub TIESCALAR { bless {}, shift }
    sub FETCH { (caller)[2] }
}

tie my $LINE, 'LineNumber';
print "Line $LINE\n";
print "Line $LINE\n";

[download]

In reply to Re: Is there a better way to use the line number in a quoted string than __LINE__? by haukex
in thread Is there a better way to use the line number in a quoted string than __LINE__? by davidfilmer

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.