From: Robert Feldt <feldt@...>
Date: 2003-09-12T22:02:36+09:00
Subject: Re: OO Challenge

Henry Gilbert <nospam@alliancetec.com> skrev den Fri, 12 Sep 2003 21:37:04 +0900:

> record tax_payer(salary,member_of)
> record tax_rule_data(multiplier, additional)
> global tax_rule
>
> procedure tax(payer)
> � � res:=0
> � � every r:=tax_rule[! payer.member_of ] do
> � � � � � � � if res less_than t:=payer.salary/r[1]+r[2]
> � � � � � � � � � � � � � � � � � � � � then res:=t
> � � return res
> end
>
> procedure main()
> � � tax_rule:=table()
> � � tax_rule["soldier"]:=tax_rule_data(10,0)
> � � tax_rule["professor"]:=tax_rule_data(15,100)
> � � A:=tax_payer(1000,["soldier","professor"])
> � � write(tax(A))
> end
>
Without any refactoring or rethinking of his "problem" here
is a Ruby version:

Rule = Struct.new("Rule", :multiplier, :additional)
class Rule
  def calc_tax(salary)
    salary/(multiplier || 1) + (additional || 0)
  end
end

Rules = {"soldier" => Rule.new(10.0, 0), "professor" => Rule.new(15.0, 100)}

TaxPayer = Struct.new("TaxPayer", :salary, :member_of)
class TaxPayer
  def tax
    Rules.select {|n,r| member_of.include?(n)}.map do |profession, rule|
      rule.calc_tax(salary)
    end.max end
end

a = TaxPayer.new(1000, ["soldier", "professor"])
p a.tax # => 166.666666667

Not the way I would structure this but its close to his code.
Which one is more "elegant" is subjective IMHO but I don't think
he has got a strong case... ;)

It also seems like a lousy example for comparisons between languages
and paradigms. Then again most such comparisons are a lousy idea... ;)

Regards,

Robert