From: Robert Klemme <bob.news@...>
Date: 2004-08-17T03:21:01+09:00
Subject: Re: A method for summing several variables


"Harry Truax" <htruax@stf.com> schrieb im Newsbeitrag
news:019801c483b7$4b338d20$1000000a@corp.stf.com...
> Thanks Austin,
>
> But unfortunately $SAFE needs to be set to 3 which will preclude the use
of
> eval( ).

You can set up an evaluator before you switch to $SAFE 3 if you know the
variables beforehand, IMHO that should work:

box1_1 = nil
box1_2 = nil
sum_up = eval( "lambda { " + ((1..2).map {|i| "(box1_#{i} ||
0).to_f" }.join( " + " )) + "}" )
$SAFE = 3
box1_1 = '10'
box1_2 = '20'
p sum_up.call

But personally, I'd prefer a different approach, where you store values
either in an array or you store the UI elements (or whatever your boxes are)
in some kind of container (array, matrix whatever).  That's IMHO a better
soltution, but then again I don't know your exact scenario since I didn't
follow the original thread.

Regards

    robert


>
> Harry
>
> ----- Original Message ----- 
> From: "Austin Ziegler" <halostatue@gmail.com>
> To: "ruby-talk ML" <ruby-talk@ruby-lang.org>
> Sent: Monday, August 16, 2004 1:13 PM
> 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
> >
> >
>
>
>