Question

my $target_type = (defined($item->{target_type}) && $item->{target_type}) 
                ? $item->{target_type} 
                : "";

my $target_id   = (defined($item->{target_id}) && $item->{target_id})
                ? $item->{target_id} 
                : "";

Why did the developer use && with almost the same conditions?

Answer 1

Apparently he’s the belt and suspenders type. (defined($x) && $x) is almost equivalent to just $x, because undef is false. (The difference is that if $x is undef then (defined($x) && $x) will be Perl’s special false value, which is defined, but in this case that makes no difference.) Possibly there used to be a different condition (like $x > 0) and the defined test was necessary to avoid a warning about an uninitialized value. Then someone removed that condition and didn’t think to remove the now-unnecessary defined.

Another reason for using (defined($x) && $x) (as onon15 points out) is to emphasize to future maintenance programmers that $x might not be defined. Personally, I would use a comment for that, but TIMTOWTDI.