Package TWiki::ListIterator

Iterator over a list


Create a new iterator over the given list. Designed primarily for operations over fully defined lists of object references. The list is not damaged in any way.

hasNext() -> $boolean

Returns false when the iterator is exhausted.

my $it = new TWiki::ListIterator(\@list);
while ($it->hasNext()) {

next() -> $data

Return the next entry in the list.

The iterator object can be customised to pre- and post-process entries from the list before returning them. This is done by setting two fields in the iterator object:

  • {filter} can be defined to be a sub that filters each entry. The entry will be ignored (next() will not return it) if the filter returns false.
  • {process} can be defined to be a sub to process each entry before it is returned by next. The value returned from next is the value returned by the process function.

For example,

my @list = ( 1, 2, 3 );

my $it = new TWiki::ListIterator(\@list);
$it->{filter} = sub { return $_[0] != 2 };
$it->{process} = sub { return $_[0] + 1 };
while ($it->hasNext()) {
    my $x = $it->next();
    print "$x, ";
will print
2, 4
Topic revision: r1 - 2008-01-22 - TWikiContributor
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