From: Simon Strandgaard <qj5nd7l02@...>
Date: 2003-11-20T22:52:14+09:00
Subject: [ann] iterator 0.1

homepage:
http://raa.ruby-lang.org/list.rhtml?name=iterator

download:
http://rubyforge.org/download.php/213/iterator-0.1.tar.gz


About
=====

If Ryby's native iterators (yield+each) ain't flexible enough,
you may want to try using this collection of bidirectional 
iterator classes.  Building custom iterator classes are simple. 
This is a simple implementation of GoF iterator-pattern.



Status
======

The overall design are stable. I don't expect any big changes.

   Collection,   iterates over an Array or similar containers.
   Reverse,      decorator which reverses the iterator.
   Range,        iterate in the range between two iterators.
   Concat,       concat multiple iterators into one.
   Continuation, turn #each_word/#each_byte into an iterator.



License
=======

Ruby's license.



Example
=======

We can virtually concatene two arrays, so that they appear 
as they were a single array.

	def test_concat_sort
		i1 = [5, 3, 1].create_iterator
		i2 = [2, 4, 6].create_iterator
		iterator = Iterator::Concat.new(i1, i2)
		assert_equal((1..6).to_a, iterator.sort)
	end


The iterator base class looks like this.
Please comment on this interface. Is it OK?
Does it need anything?

class Iterator
	# close iterator after usage.
	def close

	# set position at first element
	def first

	# goto next element
	def next

	# true if we have reached the end
	def is_done?

	# set position at last element
	def last

	# goto previous element
	def prev

	# get the value of current element
	def current

	# set the value of current element
	def current=(value)

	# iterate over all elements (forward)
	def each

	# iterate over all elements (backward)
	def reverse_each

	# create a reverse iterator
	def reverse

	# typical enum methods also
	include Enumerable
end 



Authors last words
==================

We are curios to hear what your first-impression are, What do 
you want from 'iterator.rb'? What are your requirements? 
Please contribute with extensions or suggestions. In case you 
observe bugs or other misbehavier, then please drop us a mail.

Messages must be submitted via this web-forum (prefered way of contact):
http://rubyforge.org/forum/forum.php?forum_id=46


--
Simon Strandgaard