Beefy Boxes and Bandwidth Generously Provided by pair Networks
Problems? Is your data what you think it is?

Comment on

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

>However I'd be interested to know in what case would you really want to write such code?

As already said my is much younger than foreach and it's consistent and backward compatible.

While looping over localized globals could also be done with an extra local $packvar=$lex_for_var, the aliasing effect of foreach can't be achieved in any other way in core Perl.

$\="\n"; our $foo; sub f { $foo++ } my ($a,$b,$c)=(0)x3; for $foo ($a,$b,$c) { f(); # increments $a,$b,$c } print ($a,$b,$c); #: 111 for my $foo ($a,$b,$c) { f(); # nada } print ($a,$b,$c); #: 111 for my $x ($a,$b,$c) { local $foo=$x; f(); # nada } print ($a,$b,$c); #: 111 { my $foo; sub g { $foo++ } for $foo ($a,$b,$c) { g(); # nada (irritatingly) } print ($a,$b,$c); #: 111 }

For a detailed discussion, see How do closures and variable scope (my,our,local) interact in perl?.

Cheers Rolf

UPDATE: expanded code, fixed typos

In reply to Re^6: why need my in a foreach loop? (Aliasing) by LanX
in thread why need my in a foreach loop? by szabgab

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?

    What's my password?
    Create A New User
    and all is quiet...

    How do I use this? | Other CB clients
    Other Users?
    Others meditating upon the Monastery: (4)
    As of 2018-05-27 14:17 GMT
    Find Nodes?
      Voting Booth?