I'll echo several people and say that undef is not 0 and if there is no difference between the function returning 0 and it returning undef, then the function needs to be fixed to stop returning useless undefs. If there is a difference, then you need to not only tell Perl but tell whoever will next maintain your code that you consciously want to treat undef as if it were 0 because in this specific case that makes sense.

And trying to optimize 0.5% out of one tiny part of your code (so that your total CPU savings are more like 0.005%) at the cost of less clear code is madness.

But, I do feel your pain when it comes to dealing with undefined values without generating warnings. This is such a common problem that over and over again someone proposes an alternate form of ||, call it ||| this time, that works on undefinedness instead of falseness. That way you can write: 

    my $x= some_sub() ||| 0;

[download]
or
    my $x= some_sub();
    $x |||= 0;

[download]
Now in this case, || and ||= actually work just fine. But if you wanted to treat undef as -1, for example, then || would also treat 0 as -1 (probably not what you want). This has been spinning around in my head for some time and def -- Deal nicely with undefined values is what has finally popped out. You'd use it like: 
    my $x= def( some_sub(), -1 );

[download]
or
    my $x= some_sub();
    def( $x, -1 );

[download]
With no second argument, it defaults to "", which is what I find I want the most often. In a void context it actually modifies its first argument. If you pass in a true value as a third argument, then def() modifies its first argument even if def() isn't used in a void context.

        - tye (but my friends call me "Tye")

In reply to (tye)Re: To warn or not to warn, that is the question by tye
in thread To warn or not to warn, that is the question by Ovid

Title:
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, details, 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, summary, 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.