From: dblack@...
Date: 2002-11-27T04:02:23+09:00
Subject: Re: each_with_index & collect_with_index?

Hi --

On Wed, 27 Nov 2002, ahoward wrote:

> On Wed, 27 Nov 2002 dblack@candle.superlink.net wrote:
>
> [snip]
> D> It could get unclean in a hurry, though :-)
> D>
> D>   class Thing < Array
> D>     def meth(other)
> D>       a = collect { |e| do_something_with(e) }
> D>       b = collect_with_index(self,other)...      # ugh
> D>       ...
> D>     end
> D>   end
> [snip]
>
> i'm unclear as to what you mean :
>
>   a = collect { |e| do_something_with(e) }
>
> this would be Array#collect, what does it have to do with the following line?
>
>   b = collect_with_index(self,other)...
>
> i don't really understand to point of the example.
>
> and why 'ugh'?  you have to have, at minimum, one method name and a name for
> each Enumerable in the argument list : how could it get any
> moresuccinct than that?  if you have a better suggestion i can
> incorporate it and post it...

What I don't like is the idea that #collect and #collect_with_index
behave so differently: one being an iterator instance method, the
other a kind of utility/batch-iterator.

> on second thought i would like to retract earlier statements about those
> methods belonging in Kernel (what was i thinking ) and say those methods
> should go in Enumerable as module methods so the above would need be
>
>   b = Enumerable.collect_with_index(self,other)...
>
> i've updated
>
>   http://eli.fsl.noaa.gov/lib/ruby/site_ruby/1.6/enumerable.rb
>
> to reflect this.
>
> i think we may be at cross-purposes : what i'm suggesting are methods which
> operate over n Enumerable items in synchronicity - not instance methods to be
> inherited by classes mixing in Enumerable... was this clear?

We're not at cross purposes -- that is, I understood what you meant.
I just disagree :-)  I think collect_with_index belongs among the
instance method of enumerables, just like collect, each, and
each_with_index.


David

-- 
David Alan Black
home: dblack@candle.superlink.net
work: blackdav@shu.edu
Web:  http://pirate.shu.edu/~blackdav