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README  view on Meta::CPAN

      either remove duplicates on each update by that keeping the array
      always unique or remove duplicates just before you want to use the
      uniqueness feature of the array. In either case you might run a
      function you call @a = unique_value(@a);

      The problem with this approach is that you have to implement the
      unique_value function (see later) AND you have to make sure you don't
      forget to call it. I would say don't rely on remembering this.

      There is good discussion about it in the 1st edition of the Perl
      Cookbook of O'Reilly. I have copied the solutions here, you can see
      further discussion in the book.

      Extracting Unique Elements from a List (Section 4.6 in the Perl
      Cookbook 1st ed.)

      # Straightforward

       %seen = ();
       @uniq = ();
       foreach $item (@list) [
           unless ($seen{$item}) {
             # if we get here we have not seen it before
             $seen{$item} = 1;
             push (@uniq, $item);

lib/Array/Unique.pm  view on Meta::CPAN

our $VERSION = '0.09';

# Strips out any duplicate values (leaves the first occurrence
# of every duplicated value and drops the later occurrences).
# Removes all undef values.
sub unique {
    my $self = shift; # self or class

    my %seen;
    my @unique = grep defined $_ && !$seen{$_}++, @_;
    # based on the Cookbook 1st edition and on suggestion by Jeff 'japhy' Pinyan
    # fixed by  Werner Weichselberger
}


sub TIEARRAY {
    my $class = shift;
    my $self = {
        array => [],
        hash => {},
        };

lib/Array/Unique.pm  view on Meta::CPAN

always unique or remove duplicates just before you want to use the 
uniqueness feature of the array. In either case you might run a 
function you call @a = unique_value(@a);

The problem with this approach is that you have to implement 
the unique_value function (see later) AND you have to make sure you 
don't forget to call it. I would say don't rely on remembering this.
 

There is good discussion about it in the 1st edition of the 
Perl Cookbook of O'Reilly. I have copied the solutions here, 
you can see further discussion in the book.

Extracting Unique Elements from a List (Section 4.6 in the Perl Cookbook 1st ed.)

# Straightforward

 %seen = ();
 @uniq = ();
 foreach $item (@list) [
     unless ($seen{$item}) {
       # if we get here we have not seen it before
       $seen{$item} = 1;
       push (@uniq, $item);