Carping in DESTROY.

eff_i_g has asked for the wisdom of the Perl Monks concerning the following question:

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;
}
[download]

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

Comment on Carping in DESTROY. Select or Download Code

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Re: Carping in DESTROY. by davido (Cardinal) on Oct 24, 2006 at 17:18 UTC
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";` [download] Dave	[reply] [d/l] [select]
Re^2: Carping in DESTROY. by diotalevi (Canon) on Oct 24, 2006 at 17:34 UTC
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."` [download] ⠤⠤ ⠙⠊⠕⠞⠁⠇⠑⠧⠊	[reply] [d/l]
Re^3: Carping in DESTROY. by ikegami (Patriarch) on Oct 24, 2006 at 18:01 UTC
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."` [download] This behaviour isn't new. Tested with 5.6.1	[reply] [d/l] [select]
Re^4: Carping in DESTROY. by eff_i_g (Curate) on Oct 24, 2006 at 19:10 UTC
Re^5: Carping in DESTROY. by Anonymous Monk on Oct 25, 2006 at 10:32 UTC
Some notes below your chosen depth have not been shown here
Re^2: Carping in DESTROY. by eff_i_g (Curate) on Oct 24, 2006 at 17:33 UTC
davido, I tried `die` and `eval`; neither of them show an error. I'll prepare some example code...	[reply] [d/l] [select]
Re: Carping in DESTROY. by madbombX (Hermit) on Oct 24, 2006 at 17:36 UTC
You should also be storing the object and not a reference to the object: `store \$self, DATA_FILE or warn "store error (%a): $!\n";` [download] You should also always be in the habit of checking your results (hence the `or warn "blah";`).	[reply] [d/l] [select]