From: roktas <roktas@...>
Date: 2002-02-24T17:43:00+09:00
Subject: Re: Newbie question

Hi,

* David Alan Black <dblack@candle.superlink.net> [020224 10:12]:
> Hello --
> 
> > Well... (1) I don't want to use any global var ($labels), (2) Seperating
> > 'records' and 'whole database' (DB) would be fine.
> 
> I'm not sure about (2).  Somehow the Record has to know about the
> fields in the database.  Here's one way to do it with relatively
> little overhead -- each Record has an instance variable which points
> to the relevant fields array (but doesn't duplicate that array).
> 
> 
>   class TSDB < Array
>     attr_reader :labels, :records
>     SEP = "\t"
> 
>     def TSDB.parse_line(line, sep=SEP)
>       line.chomp.strip.split(/#{sep}/)
>     end
> 
>     class Record < Array
>       attr_accessor :fields
> 
>       def initialize(line)
> 	concat(TSDB.parse_line(line))
>       end
> 
>       def [](key)
> 	at(@fields.index(key))
>       end
>     end
> 
>     def initialize(f)
>       fh = File.open(f, "r")
>       @fields = TSDB.parse_line(fh.readline)
>       push("Dummy 0th record")
>       concat (fh.readlines.map do |line|
> 	  r = Record.new(line)
> 	  r.fields = @fields
> 	  r
>       end)
>     end
>   end
> 
>   # Based on same tsd.txt file as last time:
>   t = TSDB.new("tsd.txt")
>   p t[1]["field1"]        # "one"
>   p t[2]["field2"]        # "orange"
> 
> 

This seems pretty good. I haven't even know of the nested class
definition (which is the key point in your suggestion). Himm... I should
read more documents. Thanks, regards. 

-- 
roktas