From: Austin Ziegler <halostatue@...>
Date: 2004-08-17T02:13:17+09:00
Subject: Re: A method for summing several variables

On Tue, 17 Aug 2004 01:48:09 +0900, Harry Truax <htruax@stf.com> wrote:
> Hi everyone,
> 
> Just wanted to say thank you for all of your suggestions and coding examples. I will be studying your ideas closely to see if I can implement them in our product. I really
> do not have the leeway to alter our product's code structure, I have to live with this fact (argh!!).
> 
> Our field variables (the ones we do arithematic on) are set up like:
> 
> box1_1 = ''
> box1_2 = ''
> box1_3 = ''
> box1_4 = ''
> box1_5 = ''
> box1_6 = ''
> box1_7 = ''
> box1_8 = ''
> box1_9 = ''
> box1_10 = ''
> box1_11 = ''
> etc.
> 
> The actual amount and thus naming of these variables vary from application to application. Some of the summing operations are quite lengthy as in:
> 
> box5_189 = $CUR % (box5_5.to_f + box5_10.to_f + box5_15.to_f + box5_20.to_f + box5_25.to_f + box5_30.to_f + box5_35.to_f + box5_40.to_f + box5_45.to_f + box5_50.to_f + box5_55.to_f + box5_60.to_f + box5_65.to_f + box5_70.to_f + box5_75.to_f + box5_80.to_f + box5_85.to_f + box5_90.to_f + box5_95.to_f + box5_100.to_f + box5_105.to_f + box5_110.to_f + box5_115.to_f + box5_120.to_f + box5_125.to_f + box5_130.to_f + box5_135.to_f + box5_140.to_f + box5_145.to_f + box5_150.to_f + box5_155.to_f + box5_160.to_f + box5_165.to_f + box5_170.to_f + box5_175.to_f + box5_180.to_f + box5_185.to_f + box5_187.to_f)
> 
> I will try to find a shortcut method to handle this based on your suggestions, but if I have to manually type in each box name in setting up the implementation, I may
> as well just type in the lengthy sum operation as shown above.

I didn't participate in the initial round, but why not do a generator
and then eval your generated string in the current binding?

  s = (5..185).to_a.select { |e| e % 5 == 0 }.map { |e| "box5_#{e}.to_f" }
  s << "box5_187.to_f"
  box5_189 = $CUR % [eval("(#{s.join(' + ')})", binding)]

This will work so long as there's some kind of pattern you can deal
with (I don't get the box5_187 in your example, but I added it as an
exception).

I tested in irb with:

  v = (5..187).to_a
  v = v.select { |e| (e % 5 == 0) or (e == 187) }.map { |e| "box5_#{e}" }
  v << "box5_187"
  b = binding
  v.each_with_index { |e, i| eval("#{e} = 1.25", b) }
  puts box5_10 # => 1.25
  $CUR = "%020.10f"

    # the above set the test data; the below is the implementation
  s = (5..187).to_a.select { |e| (e % 5 == 0) or (e == 187) }
  s.map! { |e| "box5_#{e}.to_f" }
  box5_189 = $CUR % [eval("(#{s.join(' + ')})", binding)
  puts box5_189 # => 000000047.5000000000
  puts v.size  * 1.25 # => 47.5

-austin
-- 
Austin Ziegler * halostatue@gmail.com
               * Alternate: austin@halostatue.ca