From: michael libby <x@...>
Date: 2002-08-24T22:56:08+09:00
Subject: Re: eval in class method

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On Saturday 24 August 2002 07:22, michael libby wrote:
>   irb(main):011:0> class FooBar
>   irb(main):012:1> def rebaz
>   irb(main):013:2> eval("class FooBar\ndef baz\nputs
>     'foobar:rebaz'\nend\nend")
>   irb(main):014:2> end
>   irb(main):015:1> end
>   nil
>   irb(main):016:0> f.rebaz
>   nil
>
> So far nothing seems amiss. Instead of doing eval from main script,
> wrote rebaz method to do eval as instance method.
>
>   irb(main):017:0> f.baz
>   foobar:new baz
>   nil
>
> Sigh. After calling #rebaz which I thought would have changed #baz, #baz
> still acts the same-- even though, except for scope/context, the eval
> statement was the same exact statement as I used before, where #baz did
> change.

[answering my own question here...]

What I found to work as an alternative was to write a root level eval 
function and call that from within the class:

#!/usr/bin/ruby -w
def root_eval(eval_string)
  eval(eval_string)
end

class FooBar
  def baz
    puts "foobar:baz"
  end

  def rebaz(s)
    root_eval(s)
  end
end

f = FooBar.new
f.baz
f.rebaz("class FooBar\ndef baz\nputs 'foobar:bitz'\nend\nend")
f.baz

Output:
  chandler@greyhound:~/ruby$ ruby root_eval.rb 
  foobar:baz
  (eval):2: warning: discarding old baz
  foobar:bitz
  chandler@greyhound:~/ruby$ 

Which is perfect! Now my text editor can edit and reload its own code 
without a restart. 

<loud joy over Ruby>

 -michael

++++++++++++++++++++++++++++++++++++++++++
Michael C. Libby <x@ichimunki.com>
public key: http://www.ichimunki.com/public_key.txt
web site: http://www.ichimunki.com
++++++++++++++++++++++++++++++++++++++++++
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