From: Shannon Fang <xrfang@...>
Date: 2005-10-25T17:16:22+09:00
Subject: Re: RCR: Array#to_h

Hi Robert,

1) Set won't work. I am not only test if an element exist or not, I want to 
assign value to the key to track its status.

2) I have not write any RCR before, so I may make mistakes. I will certainly 
propose a good use case, when I have a complete one.

3) >Problem is, that there are other conversions that are at least equally
>reasonable (e.g. the one Nobu presented).  IMHO there is not a single
>reasonable way to implement Array#to_h so it's better to leave it out.
>Maybe it's just a naming issue though.

Yes I agree it is a name issue.

Thanks,
Shannon


>From: "Robert Klemme" <bob.news@gmx.net>
>Reply-To: ruby-talk@ruby-lang.org
>To: ruby-talk@ruby-lang.org (ruby-talk ML)
>Subject: Re: RCR: Array#to_h
>Date: Tue, 25 Oct 2005 16:32:02 +0900
>
>Shannon Fang wrote:
> > Hi Matz,
> >
> >> Rejected.  Proposal Array#to_h(value=nil) does not actually solve the
> >> problem above.  If you want to have _this_ to_h, you need to have
> >> a proper usecase.
> >
> > I don't know what you mean the "problem above"... My purpose is to
> > have a convenient way to convert array to hash for *indexing* or
> > *fast searching* purpose.
>
>If you just want a fast access to those elements a Set is sufficient - and
>you can use #to_set already:
>
> >> require 'set'
>=> true
> >> a=%w{foo bar baz}
>=> ["foo", "bar", "baz"]
> >> s=a.to_set
>=> #<Set: {"baz", "foo", "bar"}>
> >> s.include? "foo"
>=> true
> >> s.include? "fo"
>=> false
>
> > This indeed is a bit ad-hoc, but it is useful in may cases.
>
>I think Matz just asked you to present these use cases.  Apart from your
>general description I couldn't find one in the thread.  Did I miss
>something?
>
> > I
> > deliberately wanted to map array value (not index) to hash key...
> > otherwise I think it is not useful (i.e., map array key => hash key).
>
>Problem is, that there are other conversions that are at least equally
>reasonable (e.g. the one Nobu presented).  IMHO there is not a single
>reasonable way to implement Array#to_h so it's better to leave it out.
>Maybe it's just a naming issue though.
>
>Kind regards
>
>     robert
>
>