Carping in DESTROY.

[eff_i_g]

Monks,

I'm calling Storable's store within a DESTROY method, and I'm not getting an error for a read-only file. I was (still am) very puzzled, but I eventually received the error by changing "DESTROY" to "end" and explicitly calling $object->end();.

Why am I not getting the error in DESTROY, and how can I handle this properly? A tiny code snippet is below, which works properly when DATA_FILE is writeable:

sub DESTROY {
    my $self = shift;
    store $self, DATA_FILE;
}

I appreciate the help as I venture further into OOP :)

[davido]

Storable's documentation states that store() returns undef on failure, and that failure usually indicates an IO error. Thus, you should be checking its return value just as you would check the return value of other IO calls.

store $self, DATA_FILE or die "Couldn't store object.\n";

[diotalevi]

I don't know where this is documented but die() in DESTROY isn't thrown on my 5.8.7.

sub A::DESTROY { die 'ok' }
my $obj = bless [], 'A';
$obj = ''; # no exception occurs
print "$@\n"; # "        (in cleanup) ok at - line 1."

[ikegami]

It does get thrown — anything after the die won't get executed — but it's intercepted by DESTROY's caller.

my $var = 1;
sub A::DESTROY { $var = 2; die 'ok'; $var = 3; }
my $obj = bless [], 'A';
$obj = ''; # no exception occurs
print "$var\n"; # 2
print "$@\n";   # "        (in cleanup) ok at - line 1."

This behaviour isn't new. Tested with 5.6.1

[eff_i_g]

davido,

I tried die and eval; neither of them show an error. I'll prepare some example code...

[madbombX]

You should also be storing the object and not a reference to the object:

store \$self, DATA_FILE 
  or warn "store error (%a): $!\n";

You should also always be in the habit of checking your results (hence the or warn "blah";).