From: RichardOnRails <RichardDummyMailbox58407@...>
Date: 2011-01-17T23:45:38+09:00
Subject: Re: A tad of meta-programming needed

On Jan 17, 1:05 am, Josh Cheek <josh.ch...@gmail.com> wrote:
> [Note:  parts of this message were removed to make it a legal post.]
>
> On Sun, Jan 16, 2011 at 11:30 PM, RichardOnRails <
>
>
>
> RichardDummyMailbox58...@uscomputergurus.com> wrote:
> > I've got the following hash set up and it works fine.  But this took
> > more typing than programming.
>
> >        h = {:name=>$1,  :n_shares=>$2,  :opened_MDY=>$3,  :closed_MDY=>$4,
> >                :proceeds=>$5,  :cost=> $6,   :gain_Loss=>$7
> >              }
>
> > So I'd like to get the following to work:
>
> >        field_names =%w<Name Shares Opened_MDY Closed_MDY Proceeds Cost
> > GainLoss>
> >        h = {}
> >        (1..field_names.size).each { |i| h[field_names[i]] = eval($ +
> > i.to_s) }
>
> > But concatenating the character "$" with the value of i converted to a
> > string, followed be evaluating that as a local variable isn't working
> > as I coded it.  Can it be easily corrected?
>
> > Thanks in Advance,
> > Richard
>
> The matchdata object implements the same inteface as a hash. If that is all
> you need, on 1.9 you could just name the capture groups, then use the
> MatchData object and not have to do any assignment/creation at all.
> (Assuming this data is based on the pastie you posted earlier, this code
> would work)
>
> RUBY_VERSION # => "1.9.2"
>
> line = "Apple 1.1234 1/2/3 4/5/6 $1,234.56 $7 ($5)"
>
> regex = /^(?<name>       .+                       )\s
>           (?<n_shares>   \d+\.\d{4}               )\s+
>           (?<opened_MDY> \d\d?\/  \d\d?\/  \d\d?  )\s+
>           (?<closed_MDY> \d\d?\/  \d\d?\/  \d\d?  )\s+
>           (?<proceeds>   [\$\d,\.]+               )\s+
>           (?<cost>       [\$\d,\.]+               )\s+
>           (?<gain_Loss>  [\(\)\$,\d \.]+          )\s*
>         $/x
>
> result = regex.match(line)
> result                      # => #<MatchData "Apple 1.1234 1/2/3 4/5/6
> $1,234.56 $7 ($5)" name:"Apple" n_shares:"1.1234" opened_MDY:"1/2/3"
> closed_MDY:"4/5/6" proceeds:"$1,234.56" cost:"$7" gain_Loss:"($5)">
> result[ :name       ]       # => "Apple"
> result[ :n_shares   ]       # => "1.1234"
> result[ :opened_MDY ]       # => "1/2/3"
> result[ :closed_MDY ]       # => "4/5/6"
> result[ :proceeds   ]       # => "$1,234.56"
> result[ :cost       ]       # => "$7"
> result[ :gain_Loss  ]       # => "($5)"

Hi Josh,

Wow!  I posted this question ~ midnight and shutdown for the night,
except for re-reading the Reflections chapter in Pragmatic's
"Programming Ruby". 2nd ed.

Got up at 9, expecting to tackle this problem again, but first opened
this thread hopefully, and was rewarded with a tutorial on part of
MatchData applicable to my goal.  That's too good to be true.

> The matchdata object implements the same inteface as a hash. If that is all
> you need ...
That is precisely all I need.

>  on 1.9 ...
I've been running 1.8.6 for a good while.  I've been tempted to
advance to to 1.9.x in get Look Ahead or Look Behind in regex's,
whichever in missing in 1.8.6.  But now I've got a definite purpose to
upgrade!

Thank you very much for your excellent solution.  I'm burdened this
problem because the IRS wants tax reports for past years when I lost a
little money as a day trader in the stock market.  You might be
surprised at how many trades you can amass in a year if you're at it
almost every weekday each year.  The IRS has instituted a new rule
which took effect this year: brokerages must report not merely
proceeds from sales, but also the related cost and hence the gain or
loss.  Duh!  Hopefully, the new rule will preclude the recurrence of
this issue.

Best wishes,
Richard
An innocent citizen :-)

I won't need to beg for any more help for a good while, I hope.

Best wish