From: Chris Lowis <chris.lowis@...>
Date: 2007-02-20T20:08:36+09:00
Subject: Re: Help with Class design

> What you're trying to do with inject is make a more "functional"
> program; you're trying to avoid assigning to things; you're closer to
> saying what you want done, rather than how you want it done (declarative
> verses imperative style). If you start making assignments, you break
> away from that style.

I think I understand what you mean, but I am so used to programming in 
languages where assignments are common place (eg. Matlab) that I am 
struggling to adjust to this new way of thinking. For example I have a 
method :

def diff()
    result = []
    @signal.each_index do |i|
      result << @signal[i+1] - @signal[i] unless i == (@signal.length - 
1)
    end
    result
end

which takes a @signal object and returns an array of the differences 
between each successive element of signal. But now I cannot write

a = MySignal.new([1,2,3])
a.diff.variance

because diff has returned an object of class "array" and the variance 
method is not defined . How do I write "diff" in someway that it gives 
me a new "signal" instead of an array ?

Thank you all for your help !

Chris



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