I find this very surprising. But I checked it and it apparently works.

Why does this give an error: 

use strict;
sub dynamic { print "hello\n"; }

my $name = "dynamic";
&$name();

[download]
.. and yet this is ok? (they differ only in the last line) 
use strict;
sub dynamic { print "hello\n"; }

my $name = "dynamic";
&{ \&$name }();

[download]
Before seeing this, I would have bet anything that the &{\&{ ... }} operation was absolutely the same as &{...} (barring weird action-at-a-distance caused by tying, overloading, etc). In fact, I'm not sure whether to consider this a bug or not. Indeed, what is \&$name doing other than "using string as a subroutine ref", which is outlawed under strict refs?

Yet a similar idea with other kinds of refs doesn't do this. Both of these examples fail under strict refs (in my mind because @{\@{...}} is unconditionally the same thing as @{...} ): 

use strict;
our @dynamic = ("hello\n");

my $name = "dynamic";
print @$name;

[download]
use strict;
our @dynamic = ("hello\n");

my $name = "dynamic";
print @{ \@$name };

[download]
My conclusion is that there is an important distinction between naming a subroutine and invoking it, which is manifested bizarrely by different behaviors in the \&{blah} and &{blah} mechanisms.

blokhead

In reply to Re^2: subroutine refs by blokhead
in thread subroutine refs by CColin

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.