Beefy Boxes and Bandwidth Generously Provided by pair Networks
good chemistry is complicated,
and a little bit messy -LW

Comment on

( #3333=superdoc: print w/replies, xml ) Need Help??

It depends how you code. It is certainly easy to code in a way where 'undef' warnings are both common and uninteresting. And 'undef' warnings are easily the ones that are mostly likely to be annoyingly common and annoyingly uninteresting.

But I usually code in a way where 'undef' warnings are much less common and much more likely to indicate a real mistake. I only rarely find myself disabling 'undef' warnings.

My biggest disagreement with the original posting is that I've never seen "isn't numeric" be a warning that I would just ignore. That warning is almost always an indication of a serious problem when I run into it.

I've only once been bitten by a bug caused by a reference being usable as a number without warning. But I agree that this could be extremely useful to be able to flag such things. I certainly want to be able to do $ref1 == $ref2. I very, very rarely even want to do things like pack "p", $ref. And 0+$ref, especially with a literal zero like that, should probably never cause a warning. But any other uses of the numeric value from a reference should generate a warning. Unfortunately, that looks rather difficult to implement in Perl, at least in some respects. Maybe not so bad if we just add a flag to scalars.

Worse was when read-only access of undef as a reference could be fatal! But maybe all of those cases have now been fixed. I've always had a hard time remembering exactly how to reproduce this failure but gave up trying to reproduce it on a modern Perl today. I'm hopeful that this just isn't a problem in modern Perls.

- tye        

In reply to Re^3: Four annoying warnings (undef, refs) by tye
in thread Four annoying warnings by tobyink

Use:  <p> text here (a paragraph) </p>
and:  <code> code here </code>
to format your post; it's "PerlMonks-approved HTML":

  • Posts are HTML formatted. Put <p> </p> tags around your paragraphs. Put <code> </code> tags around your code and data!
  • Titles consisting of a single word are discouraged, and in most cases are disallowed outright.
  • Read Where should I post X? if you're not absolutely sure you're posting in the right place.
  • Please read these before you post! —
  • Posts may use any of the Perl Monks Approved HTML tags:
    a, abbr, b, big, blockquote, br, caption, center, col, colgroup, dd, del, div, dl, dt, em, font, h1, h2, h3, h4, h5, h6, hr, i, ins, li, ol, p, pre, readmore, small, span, spoiler, strike, strong, sub, sup, table, tbody, td, tfoot, th, thead, tr, tt, u, ul, wbr
  • You may need to use entities for some characters, as follows. (Exception: Within code tags, you can put the characters literally.)
            For:     Use:
    & &amp;
    < &lt;
    > &gt;
    [ &#91;
    ] &#93;
  • Link using PerlMonks shortcuts! What shortcuts can I use for linking?
  • See Writeup Formatting Tips and other pages linked from there for more info.
  • Log In?

    What's my password?
    Create A New User
    and all is quiet...

    How do I use this? | Other CB clients
    Other Users?
    Others avoiding work at the Monastery: (3)
    As of 2018-06-18 04:48 GMT
    Find Nodes?
      Voting Booth?
      Should cpanminus be part of the standard Perl release?

      Results (107 votes). Check out past polls.