in reply to Returning 1 entry from a conditional grep call to a hash value

If you're sure to be the only iterator on %links at one time, you can use an iteration walk: 
while (my ($key, $value) = each %links) {
  if (defined $value->{visited}) {
    ... do something with $links{$key} ...;
  )
}

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-- Randal L. Schwartz, Perl hacker

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Re: •Re: Returning 1 entry from a conditional grep call to a hash value
by S_Shrum (Pilgrim) on Mar 29, 2002 at 01:18 UTC

    Just the pessimist in me thinking:

    Will the WHILE see the additional keys that get added to %links within the IF processing block or will it only see the keys that were defined before entering WHILE?

    TIA

    ======================
    Sean Shrum
    http://www.shrum.net

[reply]
      Oh! If you'll be adding to the keylist, you should use a different approach: 
      while (1) {
  my @todo = grep ! defined $links{$_}{something}, keys %links or last
+;
  while (@todo) {
    my $one = shift @todo;
    # process $links{$one}
  }
}

      [download]
      This presumes that something eventually defines all the "something" keys. If not, you need to use a sweeping strategy instead: I've done that for one of my link checker columns.

      -- Randal L. Schwartz, Perl hacker

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