From: Sarah Allen <sarah@...>
Date: 2010-03-03T00:33:57+09:00
Subject: Re: MatchData captures... expected two items, but got one?

Robert Klemme wrote:
> Where exactly is the difference between the functionality and the 
> description?
> 
> Kind regards
> 
> robert

The docs are correct, but not particularly helpful in their description. 
It is not ideal to use a word in its definition:

captures: "Returns the array of captures"
http://ruby-doc.org/core/classes/MatchData.html#M001278

If I had looked closer at the example I might have figured it out, since 
upon reflection it is pretty standard regex.  My attempts at debugging 
with rubular further confused me since it reports two matches from the 
single capture expression.  botp pointed out that I needed to specify 
one capture per result.  Which the ruby-doc example also illustrates:

   f1,f2,f3,f4 = /(.)(.)(\d+)(\d)/.match("THX1138.").captures
   f1    #=> "H"
   f2    #=> "X"
   f3    #=> "113"
   f4    #=> "8"

I was confused by the rubular experiment and also by the String.scan 
docs http://ruby-doc.org/core/classes/String.html#M000812 where captures 
are described as "groups"... or maybe they were just referring to the 
result of evaluating the capture with a scan.

Thanks everyone for your help!

Sarah
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