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

Comment on

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

To expound on demerphq's response with an example:

Given a hash, like so:

my %test; $test{a} = 1; $test{b} = 2;
When you call a subroutine with an array or hash, it gets flattened into a list. For a hash, that means giving all of its keys and corresponding values. So this:
something(%test);
is the same as this:
something(a, 1, b, 2);
(Note that when hashes are flattened, the keys may come out in any order, so it could have also been something(b, 2, a, 1);.)

The other side of this situation is that you can fill a hash directly with a list, instead of doing each key one-at-a-time. When you assign to a hash with a list, each odd item becomes a key, and the corresponding even item is its value. So we could have filled the hash like this:

%test = (a, 1, b, 2);
and it would be exactly the same. Note that this is also the same as the more familiar:
%test = (a => 1, b => 2);
as the => is just a type of comma that auto-quotes its left side operand. Now you can see what happens:
something(%test); # is like something(a, 1, b, 2);
And inside the sub:
my %hash = @_; # is like %hash = (a, 1, b, 2);
And so it turns out that you're just doing a basic copy. The hash inside the sub will be a copy of the one you passed in.


In reply to Re: Re: Perl Internals: Hashes by kelan
in thread Perl Internals: Hashes by Kozz

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 taking refuge in the Monastery: (4)
    As of 2015-07-05 08:09 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 (61 votes), past polls