I've come across a weirdness in using Safe with just the :base_core ops, using Perl 5.005_03. I have a sub foo with a prototype of `()' (takes no args), which I can use by calling just foo. But doing so in a Safe compartment with the reval method fails; I have to add brackets, or I get "glob value trapped by operation mask". Calling with brackets works, though.

Using the :default opset works. Which op do I need to add to :base_code to allow prototype lookup to work?

The enclosed code demonstrates: 

#!/usr/local/bin/perl -w

use strict;
use Safe;

# Stuff from here will be shared into the Safe compartment
package Shared;

{
  my $n;
  sub foo() { ++$n };
}

package main;

my $cpt = new Safe;
$cpt->permit_only(':base_core');
$cpt->share_from( Shared => [qw( &foo )] );

print "foo returns ", Shared::foo, "\n"
  for (1..3);

sub safe_eval {
  my $q = shift;
  my $res = $cpt->reval($q);
  if ($@) {
    "ERROR: $@\n";
  }
  else {
    "$res\n";
  }
}

print "reval(foo) returns ", safe_eval('foo') for (1..3);
print "reval(foo()) returns ", safe_eval('foo()') for (1..3);

[download]

In reply to Prototype weirdness in Safe by ariels

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.