I personally never test $@ at all. I've seen way too many practical examples of eval failing and yet $@ being left unset so I don't consider using $@ to test whether an eval failed to be wise.

A more robust approach is: 

my $okay= eval {
    ....;
    1
};
if(  ! $okay  ) {
    warn "Error in eval: $@\n";
}

[download]

Here is a quick example of how to make eval fail and leave $@ unset: 

sub DESTROY {
    # local $@;   # Uncomment this line to "fix" this
    eval {
        # Something that might fail
        # And failure should just be ignored here
    };
}
my $okay= eval {
    my $x= bless [];
    die "The world is coming to an end!!!\n";
    1
};
if(  $@  ) {
    warn "eval failed obviously: $@\n";
} elsif(  ! $okay  ) {
    warn "eval failed silently ($@).\n";
} else {
    warn "eval succeeded.\n";
}

[download]

which produces "eval failed silently ()." for me.

I'm a bit disappointed that the authors of "Effective Perl Programming" neglected this technique. You might ask them to have that noted in the errata.

- tye        

In reply to Re: Question on "Effective Perl Programming" (;1 > $@) by tye
in thread Question on "Effective Perl Programming" by jfroebe

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