There seems to be a difference in the parsing if you put whitespace in between a subroutine name and the subroutine parameters. I imagine this is known, and probably even documented somewhere, but I haven't been able to find it. Can anyone explain the difference?

In case it's a bug: I've run the following code on two machines:
This is perl, v5.8.5 built for i386-linux-thread-multi
This is perl, v5.8.6 built for darwin-thread-multi-2level

#!/usr/bin/perl

print (sort (  f(  0 ) ));
print (sort (  f ( 0 ) ));
print (sort ( &f ( 0 ) ));
print (sort    f(  0 ) );
print (sort    f ( 0 ) );
print (sort   &f ( 0 ) );

sub f { 1 }

[download]

And get the following results

Chromium:~ lexicon$ perl -l little.pl
1
0
1
0
0
1

[download]

Update: No offense guys, but you should read the existing comments before replying to a thread. broquaint had already subtly clued me in that f gets called as the sort subroutine in some cases and noth others. I still find the difference surprising, but etcshadow addressed it as just one of those "crazy rules" perl has for ambiguous situations. etcshadow also pointed out the no op unary + operator which I had been using for years for subroutine calls as my %hash = %{+shift};. Although, really, sort &f(0) does the job and has the bonus of looking correct as well.

Update 2: I thought I should also mention, to those who aren't aware, that this will apply to a lot of situations with built in functions. print will try to call your function to get a file handle, for instance.

All the help is much appreciated, of course!

Lexicon

In reply to Unexpected difference in whitespace parsing in subroutine calls. by Lexicon

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.