From: ara.t.howard@...
Date: 2006-07-29T00:53:22+09:00
Subject: Re: Weird problem with case expressions

On Sat, 29 Jul 2006, Daniel Schierbeck wrote:

>> althogh i personally would use
>> 
>>   [Integer, String, Array].detect{|c| c === 'foo'}
>> 
>> since i can easily become a one liner, even with many classes.  if you need
>> the string then
>> 
>>   [Integer, String, Array].detect{|c| c === 'foo' and c.name.downcase}
>
> That would work, but I don't think classes and types are always the same. An
> ordered hash is still a hash, even if it doesn't descend from Hash. This
> way, all objects that respond to #to_hash is in some way a hash, and I can
> trust (to some degree) that the object returned when calling that method
> implements the interface of Hash.

indeed.  still, the technique is more compact than a case:

   %w( to_int to_str to_hash to_ary ).detect{|m| 'foo'.respond_to? m}

and, for returning values

   {
     'to_int'  => 'integer',
     'to_str'  => 'string',
     'to_hash' => 'hash',
   }.detect{|m,s| break s if 'foo'.respond_to? m}

note that this returns 'nil' when no match is found.  but this isn't quite as
compact.

cheers.

-a
-- 
we can never obtain peace in the outer world until we make peace with
ourselves.
- h.h. the 14th dali lama