[tpm] Attempt to free unreferenced scalar

[Fulko Hew]

On Wed, Jun 23, 2010 at 10:35 PM, Mike Stok <mike at stok.ca> wrote:

>
> On Jun 23, 2010, at 7:22 PM, Fulko Hew wrote:
>
>
> I'm in the process of developing a module, and during a very simple
> test (when the program exits, and things get auto-cleaned-up, I get the
> following error message:
>
> Attempt to free unreferenced scalar: SV 0x8c1cc28, Perl interpreter:
> 0x8c1c008.
>
> I know I'm probably doing something wrong somewhere, or better put:
> 'I'm not doing something I should be doing', but...
>
> Whats the process of trying to figure out whats causing this error?
> How do I find out what was in the variable at '0x8c1cc28'?
> If I knew that, I may be able to figure out whats wrong.
>
> Suggestions anyone?
>
>
> What version of perl?  I have seen problems reported with 5.10.0 which were
> fixed in 5.10.1 e.g.
> http://www.gossamer-threads.com/lists/engine?do=post_view_printable;post=245361;list=perl
>

Specifically version 5.8.8.
And yes, I saw the issues with specific versions, but I felt it was an issue
with
my code.  I've solved it (details below), but my generic question remains:

"Given a memory address, how can I dump the contents of the associated
variable?"

I see a number of modules on CPAN to: dump the internal structure of
scalars,
dump symbol tables, dump memory usage of variables, etc.
but not a 'dump the variable at a memory location'.

If I had something like that, I could have seen the value of the data, and
immediately recognized where that data was being generated and stored.

OK... Back to _my_ problem.

It turned out that I was storing a global variable into a hash element
inside an object.
Once I made it a 'my' variable, the problem went away.  The (bad) pseudo
code would be:

foreach $name (@names) {
   MYCLASS->new(name=>$name);
}

whereas it should have been:

foreach my $name (@names) {
   MYCLASS->new(name=>$name);
}
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