Kernel#eval and class definition

ruby-talk
1

Lähettäjä: Bertram Scharpf <lists@bertram-scharpf.de>
Aihe: Kernel#eval and class definition

Hi,

I try to understand more deeply what Ruby does.
Why here is the first line forbidden, the second allowed?

    def f ; class C ; end ; end
    def f ; eval "class C ; end", binding ; end

Thanks for your answers in advance.

I'm assuming you have something passed to the function that you need
the binding for? Are you getting an error? You may want to try to
establish the binding before the eval call and see if that helps.

Bertram

E

2

That shouldn't make a difference and, as far as I see, it
doesn't.

irb(main):001:0> def f ; class C ; end ; end
SyntaxError: compile error
(irb):1: class definition in method body
def f ; class C ; end ; end
                 ^
        from (irb):1
irb(main):002:0> def f ; eval "class C ; end", binding ; end
=> nil
irb(main):003:0> def f x ; y = x ; eval "class C ; end", binding ; end
=> nil
irb(main):004:0>

Bertram

···

Am Mittwoch, 12. Jan 2005, 05:06:36 +0900 schrieb E S:

> Lähettäjä: Bertram Scharpf <lists@bertram-scharpf.de>
> Aihe: Kernel#eval and class definition
>
> Hi,
>
> I try to understand more deeply what Ruby does.
> Why here is the first line forbidden, the second allowed?
>
> def f ; class C ; end ; end
> def f ; eval "class C ; end", binding ; end
>
> Thanks for your answers in advance.

I'm assuming you have something passed to the function that you need
the binding for? Are you getting an error? You may want to try to
establish the binding before the eval call and see if that helps.

--
Bertram Scharpf
Stuttgart, Deutschland/Germany
http://www.bertram-scharpf.de