From: Robert Klemme <bob.news@...>
Date: 2005-07-12T20:20:52+09:00
Subject: Re: accessing index inside map

Brian Candler wrote:
>> IMHO the enumerator approach is slightly superior as your suggestion
>> can lead to conflicts with current method arguments as you have
>> noticed. Personally I don't have a problem using
>>
>> a.to_enum(:each_with_index).inject(0) {|sum,(a,i)| sum + a*i}
>>
>> I think this is more flexible and modularized.  And the overhead of
>> a new instance creation is usually neglectible compared to the
>> iteration overhead.
>
> "Do the simplest thing which will possibly work" :-)

Well, apparently we have differing opinions on this.  Personally I find
the Enumerator approach simpler as it does not clutter the original's
class interface (introducing an optional parameter on each method doubles
the number of legal invocations). :-)

> Actually I think my version reads better:
>
>   a.inject(0,:each_with_index) {|sum,(a,i)| sum + a*i}
>
> "Starting with 0, call :each_with_index with the following block".

There is a chance that folks who don't know #inject might read "start with
index 0".

Well, I think a vote is in order.  Did you consider submitting this as
RCR?

Kind regards

    robert