From: Robert Klemme <bob.news@...>
Date: 2004-05-07T17:38:57+09:00
Subject: Re: [ann] iterator-0.7


"Simon Strandgaard" <neoneye@adslhome.dk> schrieb im Newsbeitrag
news:20040506182920.02fd89f5.neoneye@adslhome.dk...
> "Robert Klemme" <bob.news@gmx.net> wrote:
> > "Simon Strandgaard" <neoneye@adslhome.dk> schrieb im Newsbeitrag
> > news:20040506120251.43669286.neoneye@adslhome.dk...
> > > homepage:
> > > http://raa.ruby-lang.org/list.rhtml?name=iterator
> > >
> > > download:
> > > http://rubyforge.org/frs/?group_id=18&release_id=467
> > >
> > >
> > > External iterators with some STL inspiration.
> [snip]
> > Great!  This looks good.  I'd just do some small interface changes.
> >
>
> I am always open to suggestions ;-)
>
>
> > Move Array#create_iterator to Enumerable and rename it to
> > Enumerable#iterator (we're lazy typers) if possible.
>
> Good suggestion.. will change it.
>
>
> > Alternatively you could provide this wrapper:
> >
> > module Enumerable
> >   def iterator; Iterator::Continuation.new(self, :each); end
> > end
> >
>
> Also a good suggestion.. will change it.
>
>
>
> > Make Iterator::Concat#initialize to be able to do
> > iterator = Iterator::Concat.new(i1, i2, i3) # brackets removed
> > iterator = Iterator::Concat.new(i1, ary2, i3)
> >
>
> Major dillema, I don't know how to do it.
> My current Concat#initialize looks like  "def initialize(iterators,
position=nil)"

Ah, I see.

> If I do "def initialize(*iterators, position=nil)".. that won't work ?
>
> irb(main):001:0> def m(*args, x=nil)
> irb(main):002:1> p args
> irb(main):003:1> p x
> irb(main):004:1> end
> SyntaxError: compile error
> (irb):1: syntax error
> def m(*args, x=nil)
>               ^
> (irb):1: syntax error
>         from (irb):1
> irb(main):005:0>
>
> Any hints on how to pass 'position' to initialize ?

def init(*args)
  if Numeric === args[-1]
    pos = args[-1]
    args.slice!(-1, 1)
  else
    pos = nil
  end

  puts "iterators: #{args.inspect}"
  puts "position : #{pos.inspect}"
end

irb(main):066:0> init "a","s",1
iterators: ["a", "s"]
position : 1
=> nil
irb(main):067:0> init "a","s"
iterators: ["a", "s"]
position : nil
=> nil
irb(main):068:0> init
iterators: []
position : nil
=> nil

Or even

def init2(*args)
  pos = nil
  iters = []

  args.each do |arg|
    case arg
      when Numeric
        raise ArgumentError, "duplicate start positions" if pos
        pos = arg
      when Iterator # place appropriate type(s) here
        iters << arg
      when Enumerable
        iters << Iterator::Continuation.new(arg, :each)
      else
        raise ArgumentError, "Don't know what to do with #{arg.inspect}"
    end
  end

  puts "iterators: #{iters.inspect}"
  puts "position : #{pos.inspect}"
end


> > Nice to have but maybe not worth the effort:
> > Iterator#reset
>
> Its already there.. #first  and  #last  both resets the iterator.

Ooops, overlooked that one.

> Thanks for these great suggestions.. keep them coming.

You're welcome.

Kind regards

    robert