Beefy Boxes and Bandwidth Generously Provided by pair Networks
"be consistent"
 
PerlMonks  

comment on

( #3333=superdoc: print w/replies, xml ) Need Help??
Can you monks please explain step-by-step what computations will happen here?

Under strict, none, because it will not compile unless $x, $y, and $z have been previously declared. Otherwise, B::Deparse helps:

$ perl -MO=Deparse,-p -e 'my $a, $x, $y, $z = foo()' (my($a), $x, $y, ($z = foo()));

In other words, it's declaring a lexical $a, then $x and $y are simply sitting there, and then $z is assigned the return value of the function call foo() - although if that's not defined, that call will fail. See also Comma Operator. Turning on warnings gives some relatively helpful hints:

$ perl -w -e 'my $a, $x, $y, $z = foo()' Parentheses missing around "my" list at -e line 1. Useless use of a variable in void context at -e line 1. Useless use of a variable in void context at -e line 1. Name "main::x" used only once: possible typo at -e line 1. Name "main::z" used only once: possible typo at -e line 1. Name "main::y" used only once: possible typo at -e line 1. Undefined subroutine &main::foo called at -e line 1.

In reply to Re: What's happening in this expression? by haukex
in thread What's happening in this expression? by zapdos

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, 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?
    Username:
    Password:

    What's my password?
    Create A New User
    Chatterbox?
    and the web crawler heard nothing...

    How do I use this? | Other CB clients
    Other Users?
    Others rifling through the Monastery: (6)
    As of 2021-01-21 12:19 GMT
    Sections?
    Information?
    Find Nodes?
    Leftovers?
      Voting Booth?
      Notices?