Yes, they are memory locations and could be more or less useful with a core file. It would take a good knowledge of perl implementation details to make that meaningful. A perl built with -DDEBUGGING is probably a better investment for such an investigation.

You can get the decimal address with print 0 | $ref;, which places $ref in numeric context. Since | acts on bitfields, $ref's target address is coerced into an unsigned integer.

I just use "0 + $ref". Maybe that's a holdover from my many years of awk programming.

-- Randal L. Schwartz, Perl hacker
Be sure to read my standard disclaimer if this is a reply.

Yes, it makes no difference. It looks like a reference is always unsigned in numeric context, since 0+ gives the same result as 0|, while 0x8nnnnnnn would be negative taken as a 32 bit signed integer.

After Compline,
Zaxo

Dave.

And you can actually get to them using Devel::Pointer.

use Devel::Pointer;

$a = 'Hello World';
$scalar_ref = \$a;
print "Scalar Ref is $scalar_ref\n";
$what = unsmash_sv(0+$scalar_ref);
print "$scalar_ref is actually >$what<\n";

__DATA__
Scalar Ref is SCALAR(0x1ab2734)
SCALAR(0x1ab2734) is actually >Hello World<
[download]

cheers

tachyon

This is probably a silly questions, but my inexperience with memory management forces me to post it. ;-)

So, those references are actually pointers which map directly to system memory. However, if the systems moves around memory zones (i.e. it puts something on the swap file/partition), how can they remain valid?

Thanks, Michele.

The addresses programs use are virtual addresses. These are translated to real (physical) addresses by the OS and/or the CPU transparently to the program.

The following extract from here says it better.

Address translation

This means the virtual addresses generated by a program are different from the physical addresses that go onto the address bus; to the memory chips. The translation of virtual addresses to physical addresses is performed by special hardware inside the CPU called a memory management unit (MMU).

Address translation can be used for the kernel as well as the tasks. This lets you link the kernel to run at a specific address, but load the kernel anywhere in memory.

Besides address translation, the MMU usually provides memory protection. Ranges of memory can be made to cause a page fault or general protection fault by any combination of writing to the memory range, accessing the memory range in any way (read, write, execute), access to the memory range by code running at user privilege (ring 3).

---

Examine what is said, not who speaks.

"Efficiency is intelligent laziness." -David Dunham
"Think for yourself!" - Abigail