New class: io.collections.CollectionComposite

at 2006-11-09 in Announcements by friebe (0 comments)

The new io.collections API (see entry #113 for initial announcement, here for the corresponding RFC) features a new class, CollectionComposite (apidocs).

Its purpose is to ease iteration on more than one collection (of any kind: one could combine a file collection with an FTP collection, for example); while previously one while-loop would be needed for every collection to iterate on, this can now be accomplished with one loop.

Use-case: All files in /home and /usr
Previous approach:

  $home= &new FileCollection('/home');
  $home->open();
  while (NULL !== ($element= &$home->next())) {
    Console::writeLine('- ', $element->toString());
  }
  $home->close();

  $usr= &new FileCollection('/usr');
  $usr->open();
  while (NULL !== ($element= &$usr->next())) {
    Console::writeLine('- ', $element->toString());
  }
  $usr->close();

With the new CollectionComposite class:

  $collection= &new CollectionComposite(array(
    new FileCollection('/home'),
    new FileCollection('/usr')
  ));
  $collection->open();
  while (NULL !== ($element= &$collection->next())) {
    Console::writeLine('- ', $element->toString());
  }
  $collection->close();

Of course, the CollectionComposite can also be used together with the io.collections.iterate API. But you knew that

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New class: io.collections.CollectionComposite

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