TWikiListIteratorDotPm < TWiki

Tags: view all tags

---+ Package =TWiki::ListIterator=

Iterator over a list


%TOC%

---++ new(\@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.

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


---++ 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,
<verbatim>
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, ";
}
</verbatim>
will print
<verbatim>
2, 4
</verbatim>

Topic revision: r1 - 2008-01-22 - TWikiContributor

Webs
TWiki

Account
- Log In
- Register User

Edit
Attach

Copyright © 1999-2025 by the contributing authors. All material on this collaboration platform is the property of the contributing authors.
Ideas, requests, problems regarding TWiki? Send feedback
Note: Please contribute updates to this topic on TWiki.org at TWiki:TWiki.TWikiListIteratorDotPm.