From: El Gato <wmwilson01@...>
Date: 2007-02-27T00:42:15+09:00
Subject: Subclassing Array

I'm sure I'm just being an idiot here... my mind is a little foggy this
morning, but I'm having a hard time understanding how to accomplish
this.  I've written a class (I'll just put some snippets in for
understanding) in which I'd like to be able to use the following
behavior:

irb> columns = [[1, "Hostname"], [2, "Model"], [5, "OS Version"]]
irb> report = InventoryReport.new("HARDWARE_QUERY", columns)
irb> report.query.map {|a| a.first.downcase!; a}.save "/tmp/test.xls"

Where query() returns an array like [["host1", "Dell", "Windows"],
["host2", "Hitachi", "Windows"], ...]

However, throwing a map (or select or whatever) in there (obviously)
ends up returning an Array.  How would I handle this so that it works as
I would like?  Do I need to move my save(), to_csv(), and to_xls() stuff
into the Array class?

Sorry if this is a dumb question.

class InventoryReport < Array
    def initialize(query_name, fields)
        @query_name = query_name
        @fields = fields
        super()
    end

    def query
        cols = @fields.map {|a| a.first - 1}
        %x{runquery #{@query_name}}.each_line do |l|
           t = l.chomp.split
           tmp = []
           cols.each do |a|
               tmp << t[a].strip
           end
           self << tmp
        end
        self
    end

    def save(filename)
        case filename
            when /.*\.csv/ then to_csv(filename)
            when /.*\.xls/ then
                to_csv(filename.gsub(/xls$/, "csv"))
                to_xls(filename, filename.gsub(/xls$/, "csv")
         end
    end

    def to_csv(...)
    end

    def to_xls(...)
    end
end

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