From: Simon Strandgaard <neoneye@...>
Date: 2005-04-29T01:31:15+09:00
Subject: Re: cursor/stream/c++ iterator class?

On 4/28/05, Eric Mahurin <eric_mahurin@yahoo.com> wrote:
> --- Simon Strandgaard <neoneye@gmail.com> wrote:
> > I have made a lib containing some external iterators, see:
> > http://aeditor.rubyforge.org/iterator/
> >
> > download it here:
> > http://rubyforge.org/frs/download.php/704/iterator-0.8.zip
> 
> Thanks Simon.  I just looked through what you have.  You gave
> me a few ideas.  But, here are a few things I don't like:
> 
> * for efficiency I would like the ability to read/write
> multiple elements at a time.  I want the API to have a superset
> of the features in IO if possible.

True, I didn't made mine for speed.

 
> * instead of calling has_next? I'm just having next return nil
> or an empty string/array (for getting N elements).  If the
> collection can have nil elements, you'll have to ask for N
> elements (could be 1) so that you get an empty array at the
> end.

What if you are iterating through an array that coincidentially
contains a nil.. like this [42, nil, 42]  ?

 
> * no standard insert/delete operations.  I don't need them now,
> but they might be useful to others.

Yeah, I don't have neither insert nor delete. 
I didn't needed it when I made the lib. I though about it,
but couldn't decide how to approach this problem.

 
> * like the C++ iterator, yours standardizes on
> allowing/creating/comparing multiple iterators on the same data
> structure.  I don't want to do this because many sequential
> data structures can't handle this.  The primary example would
> be an IO (especially a non-file) which only allows you to
> read/write at one location at a time.  Another would be a text
> editor buffer where you can only insert/delete at the cursor
> position.  Instead of allowing multiple iterators for a data
> structure, you'll be able to get and set the position where
> "position" is an object that you might be able to compare
> and/or do arithmetic on (depends on the data structure).

This sounds interesting.  I would be interesting at looking
at how you would approach this.

 
> I think I'll call the class I'm doing "Cursor" because it most
> resembles what you can do at the cursor in a text editor and
> I've also seen the term "cursor" used for external iterator.
> 
> I might take some of the ideas in your Iterator classes also
> (some from C++ STL iterator it looks like), if you don't mind.

Feel free to use all of it as you like. 
Is your project on rubyforge ?

--
Simon Strandgaard