Re^2: Dealing with errors in subroutines

Somewhere along the way I picked up the habit of writing this idiom so:

for (@users) { 
    my $success = eval { 
        add_account($_); 
    }; 
    if($@ or not $success) {
        warn "Can't add user '$_': $@"
    }
[download]

But I don't remember why I thought it might be better. Certainly not from readability! What do others think of this kind of double-checking?

- Boldra

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Re^3: Dealing with errors in subroutines by moritz (Cardinal) on Sep 14, 2009 at 10:48 UTC
It's not paranoid but good practice, because (as ELISHEVA pointed out below) a DESTROY method can accidentally reset the global $@ variable, as this small piece of code demonstrates: `use strict; use warnings; use Data::Dumper; sub DESTROY { eval { 1 } } eval { my $obj = bless {}; die "wrong"; }; print Dumper $@; __END__ $VAR1 = '';` [download] The correct solution is to localize $@ in the DESTROY sub, but you can't always rely on third-party modules to do such things correctly. Perl 6 - links to (nearly) everything that is Perl 6.	[reply] [d/l]

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Re^3: Dealing with errors in subroutines
by moritz (Cardinal) on Sep 14, 2009 at 10:48 UTC

ELISHEVA

use strict;
use warnings;
use Data::Dumper;

sub DESTROY { eval { 1 } }

eval {
    my $obj = bless {};
    die "wrong";
};

print Dumper $@;
__END__
$VAR1 = '';
[download]

The correct solution is to localize $@ in the DESTROY sub, but you can't always rely on third-party modules to do such things correctly.

Perl 6 - links to (nearly) everything that is Perl 6.

[reply]
[d/l]