From: "Thind, Aman" <aman.thind@...>
Date: 2008-08-11T13:39:20+09:00
Subject: Re: Expanding variables in a string

Thanks for the reply!

If I do eval(myaction) then it thinks all the words in the string are
variables and complains:

irb(main):002:0> myaction = 'perl #{ENV[HOME_SCRIPTS]}/myscript.pl
-#{params[:date]}'
=> "perl \#{ENV[HOME_SCRIPTS]}/myscript.pl -\#{params[:date]}"

irb(main):004:0> eval myaction
NameError: undefined local variable or method `perl' for main:Object

What I want is for all the known variables in the string to be expanded;
the same effect that assignment with double quotes has.
 
Please remember I know using double quotes in the assignment to myaction
would solve the problem but I am doing this assignment only for
illustration.

I actually get the string from a db query so have to expand the
variables after the assignment.

Thanks,
Aman

-----Original Message-----
From: Frantisek ZACEK [mailto:czechripper@gmail.com] 
Sent: Monday, August 11, 2008 1:07 PM
To: ruby-talk ML
Subject: Re: Expanding variables in a string

On Mon, Aug 11, 2008 at 6:00 AM, Thind, Aman <aman.thind@lehman.com>
wrote:
> Hello,
>
> If I have a string containing variables, how can I expand them?
>
> I retrieve this string from a db so I cannot expand it at the time of 
> assignment.
>
> Eg:
>
> myaction = 'perl #{ENV['HOME_SCRIPTS']}/myscript.pl -#{params[:date]}'
>
> I want to be able to do:
>
> system(myaction)
>
> but for this I have to expand the vars inside the script first.
>
> Many Thanks,
> Aman
>
>


You mean you wish to execute in Ruby code you have in a string ?

If that's wha you're looking for then eval is what you want.



--
Frantisek ZACEK (zacek_f) -- SRS 2008

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