From: Eric Mahurin <eric_mahurin@...>
Date: 2005-06-04T00:51:29+09:00
Subject: Re: internal iterators in ruby

I'm working on a very extensive package called exactly that:
Cursor.  Take a look here:

http://cursor.rubyforge.org/

It combines features from C++ iterators, Java streams, a
text-editor "cursor", and have some other unique features.

--- Robert Klemme <bob.news@gmx.net> wrote:

> Geert Fannes wrote:
> > Yes, indeed, something cursor-like. Enumerable#getCursor
> returns a
> > rewinded Cursor and Cursor#next provides the method to
> retrieve
> > subsequent elements. Does something like this already exist
> for Ruby?
> > Geert.
> 
> http://raa.ruby-lang.org/search.rhtml?search=iterator
> 
> Dunno about the internals though.
> 
> Kind regards
> 
>     robert
> 
> > 
> > -----Original Message-----
> > From: Robert Klemme [mailto:bob.news@gmx.net]
> > Sent: 03 June 2005 12:15
> > To: ruby-talk ML
> > Subject: Re: internal iterators in ruby
> > 
> > Geert Fannes wrote:
> >> So, if I understand well, the problem with iterating over
> different
> >> enumerables synchronously has to do with the absence of a
> #rewind and
> >> #next method for enumerables. The Generator class solves
> this using
> >> the slow #callcc method and allows one to step through the
> >> Enumerable#each method, element by element. Wouldn't it be
> better if
> >> the enumerable required a #rewind and #next method and
> constructs the
> >> #each method out of these instead of doing the reverse
> using #callcc?
> > 
> > No, this would not be better because then you would have to
> place
> > iteration state into the Enumerable which is at least ugly
> (it wastes
> > memory most of the time, i.e. the time when there is no
> iteration) and
> > it
> > doesn't allow for multiple concurrent iterations on the
> same instance.
> > 
> > A better alternative would be to encourage providers of
> Enumerables to
> > provide an external iterator for special cases.  This then
> will be
> > more efficient than callcc.
> > 
> > Kind regards
> > 
> >     robert
> 
> 



		
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