Re: faulty expression prob

I suspect you are running into a precedence issue, specifically with the conditional operator (?:) and the assignment operator (=). See perlop.

Personally, though, I found the code hard to read. I'd probably write it something like this:

$rh = $pkg->{'RPM_HDR'};
$dist = $rh->tag('DISTRIBUTION');

# or $dist = $pkg->{'RPM_HDR'}->tag('DISTRIBUTION');

$pkg->{DIST} = $dist ? $dist : $undef; # $undef or undef?
[download]

Update: Given how you are testing for truth, keep in mind what Perl considers to be a true value (vs a defined value). See True or False? A Quick Reference Guide for examples.

Comment on Re: faulty expression prob Download Code

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Re^2: faulty expression prob by ikegami (Patriarch) on Apr 03, 2008 at 07:55 UTC
You removed the check that prevented the method `tag` from being called on an undefined value. `$dist = $rh->tag('DISTRIBUTION');` [download] should be `$dist = $rh && $rh->tag('DISTRIBUTION');` [download] Also, `$pkg->{DIST} = $dist ? $dist : undef` [download] can be written as `$pkg->{DIST} = $dist \|\| undef` [download]	[reply] [d/l] [select]
Re^3: faulty expression prob by perl-diddler (Chaplain) on Apr 03, 2008 at 23:17 UTC
Um...somewhere along the line, someone dropped a "$" before "undef"..."$undef" != undef, but $undef = 'undef''; In answer to next Q, I did want assignments -- they needed to be evaluated or done left-to-right, where the 'right' side isn't done if the left side fails... If I wanted to use "==" instead of assignment, I would have preferred '&&' over 'and'. I try to use 'and' && 'or' when I don't want them interfering with an assignment.	[reply]
Re^4: faulty expression prob by ikegami (Patriarch) on Apr 04, 2008 at 00:32 UTC
where the 'right' side isn't done if the left side fails... That's what `$rv &&` does. Update: Hum, at first, I thought you you were disagreeing with what I posted, but I think you were just confirming what I said.	[reply] [d/l]
Re^2: faulty expression prob by apl (Monsignor) on Apr 03, 2008 at 10:59 UTC
Thanks for breaking out the assignments. I kept wondering if perl-diddler didn't actually want equality tests as opposed to assignments in his original code...	[reply]