From: "List.rb" <list.rb@...>
Date: 2009-02-03T09:12:13+09:00
Subject: Re: Is this possible in Ruby


On Feb 2, 2009, at 6:33 PM, "Sean O'Halpin" <sean.ohalpin@gmail.com>  
wrote:

> On Mon, Feb 2, 2009 at 10:49 PM, Damjan Rems <d_rems@yahoo.com> wrote:
>>
>> Just an idea which may come in handy. Can this be done and how in  
>> Ruby.
>>
>> def calc(what)
>> some_eval(what)
>> end
>>
>> a=10
>> b=12
>> calc('a+b') # expression as parameters
>> => 12   # would return
>>
>> a='aa'
>> b='bb'
>> calc('a+b')
>> => 'aabb'
>>
>> This is of course strictly hypothetical. I would like the  
>> expression to
>> be evaluated inside the method using variables which are local to the
>> calling part.
>>
>>
>> by
>> TheR
>
> ruby 1.9 comes with Binding#eval. In 1.8.6 you can do this:
>
> class Binding
>  def eval(str)
>    Kernel.eval(str, self)
>  end
> end
>
> a = 10
> b = 12
> binding.eval('a + b') # => 22
>
> def another(c, d)
>  binding.eval('c + d')
> end
> another(20, 22) # => 42
>
> Regards,
> Sean
>

I thought in 1.8.6 it could be done.. Not positive though

a, b = 3, 5
formula="a*b"
p eval(formula)