Why not think of STDIN, STDOUT and STDERR as a kind of constants? And really they look like nothing different, do they? Perl constants are used to be implemented as named subroutines with a zero-argument prototype, returning a filehandle reference.

Unfortunately however, passing an actual user-defined constant filehandle to print() will work only when wrapped in curlies, likewise would any other expression returning a filehandle:

use strict;
sub FH () { open my $fh, '>', '/tmp/testfile.txt'; $fh }
eval q{ print FH "Hello world!\n"; } or warn "Doesn't work - $@";
print {FH} "This works";

[download]

The curlies are recommended best practice for every time you must use type-globs, cf. Conway(2006). Think of it as type-glob derefencing with the star sigil omitted again.

Nowadays you should make lexical filehandles, how this is done has been already outlined in the thread.

In reply to Re: Why don't file handles have sigils? by flowdy
in thread Why don't file handles have sigils? by 1s44c

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.