Beefy Boxes and Bandwidth Generously Provided by pair Networks
laziness, impatience, and hubris
 
PerlMonks  

Comment on

( #3333=superdoc: print w/ replies, xml ) Need Help??
(Replying to the Update in the OP.)
The when ([wxID_YES]) {....} also works (why?)

I also wondered that. :-) Here is the answer I came up with:

  1. From Experimental Details on given and when, it is clear that this is not one of the “10 exceptional cases” in which the expression is treated as a boolean. Therefore, smartmatching applies.

  2. From Smartmatch Operator:

    The smartmatch implicitly dereferences any non-blessed hash or array r +eference, so the HASH and ARRAY entries apply in those cases.
  3. Also from Smartmatch Operator:

    Right operand is an ARRAY: ... Any ARRAY smartmatch each ARRAY element like: grep { Any ~~ $_ } ARRAY
  4. and

    Num nummy numeric equality like: Num == nummy

    where nummy is defined as

    Either an actual number, or a string that looks like one.

So,

when ([wxID_YES])

creates an anonymous array reference, and populates the array with the result of calling wxID_YES() — namely, 5103 — then it dereferences the array reference (1) & (2), and performs a smartmatch on the elements (3), effectively:

grep { $selection ~~ $_ } (5103)

which (4) reduces to:

$selection == 5103

which actually succeeds in being DWIM.

All clear now?   ;-)

*   *   *

Also interesting is tobyink’s observation about constant, because

use constant FOO => 42;

is implemented as a subroutine named FOO. The significant point is that this subroutine is prototyped to take no arguments:

sub FOO() { return 42; }

which (together with some other requirements) allows Perl to inline it — that is, wherever FOO appears in the code (outside of quotes), it is replaced with the value 42, so smartmatching just works as expected. See Constant Functions.

Athanasius <°(((><contra mundum


In reply to Re: converting from switch to given-when by Athanasius
in thread converting from switch to given-when by jmlynesjr

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 studying the Monastery: (5)
    As of 2015-07-05 06:55 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