Beefy Boxes and Bandwidth Generously Provided by pair Networks
Syntactic Confectionery Delight
 
PerlMonks  

Comment on

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

Fun.

The reason that using your preInc() sub changes the result is because the value it returns is a copy of $m's value at the end of the call to the sub.

By contrast, the value of $m used by the + operator in the non-sub statement is the value of $m at the point after both the subexpressions involved in the + operation have been evaluated.

I assume that the order of the evaluation is a result of converting the expressions to their reverse polish form. Clear as mud, but this is (roughly) equivalent

$m=20; $r = \$m; print ${ $$r += 1; $r } + ${ my $t=$$r; $$r += 1; \$t }; 43

At least, it produces the same result and is close enough for my mental processes to get a notional handle on the mechanism.


Examine what is said, not who speaks.
"Efficiency is intelligent laziness." -David Dunham
"Think for yourself!" - Abigail
"Memory, processor, disk in that order on the hardware side. Algorithm, algoritm, algorithm on the code side." - tachyon

In reply to Re: Quantum Weirdness and the Increment Operator by BrowserUk
in thread Quantum Weirdness and the Increment Operator by barrachois

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!
  • 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 scrutinizing the Monastery: (6)
    As of 2015-07-04 13:12 GMT
    Sections?
    Information?
    Find Nodes?
    Leftovers?
      Voting Booth?

      The top three priorities of my open tasks are (in descending order of likelihood to be worked on) ...









      Results (60 votes), past polls