From: "David A. Black" <dblack@...>
Date: 2004-09-21T20:09:35+09:00
Subject: Re: Array#index block and rdetect

Hi --

On Tue, 21 Sep 2004, Yukihiro Matsumoto wrote:

> Hi,
> 
> In message "Re: Array#index block and rdetect"
>     on Tue, 21 Sep 2004 10:56:51 +0900, "David A. Black" <dblack@wobblini.net> writes:
> 
> |Here's one possibility.  I don't think this would be bad for
> |compatibility, because Array would have its *_index methods, and I
> |don't think #each_with_index is used much (ever?) for anything except
> |arrays and maybe array subclasses.  
> |
> |  Enumerable:
> |
> |     each_with_counter   # "dumb" counters, for every enumerable,
> |     each_counter        # strictly based on incrementing through
> |                         # #each
> 
> No need for each_counter, for there's no way for general enumerables
> to map from counters to values.  If it's possible, it's rather
> suitable to be called as index.  By the way, do you agree with the
> word 'counter'?  It's kinda burden for me, non English speaker, to
> tell the word nuance.

I think it's OK.  "counter" is very similar to an expression like:
"maintaining a counter in a loop".  It also has a "dumb" sound (in a
good way :-) that keeps it separate from index and key.  (Index and
key both suggest a direct lookup, whereas counter suggests an external
numbering which could apply to a non-lookup enumerable as well as a
lookup enumerable.)  

> |  Array:
> |
> |     each_with_index     # either very similar to, or identical to,
> |     each_index          # the *_counter methods (because that
> |                         # happens to be how arrays work).
> 
> No objection here.
> 
> |  Hash and other enumerable classes:
> |
> |     In addition to the *_counter methods, each enumerable class
> |     can have its own, "smart" methods (just as Array does with
> |     its *_index methods).  They can have "index" in the name,
> |     if appropriate -- but they do not have to.  (There are no
> |     Enumerable#*_index methods.)
> 
> Do you have any opinion toward Hash#each_with_index?

I prefer "key" for hashes and "index" for arrays (I know Robert
disagrees), so I would tend to avoid "index" names for hash methods.
But I have no deep theoretical argument here.  I'm just following what
I think is common usage (index/element for array, key/value for hash).  


David

-- 
David A. Black
dblack@wobblini.net