From: Pat Maddox <pergesu@...>
Date: 2006-05-09T06:07:21+09:00
Subject: Re: Question about instance_eval

On 5/8/06, James Edward Gray II <james@grayproductions.net> wrote:
> On May 8, 2006, at 3:30 PM, Pat Maddox wrote:
>
> > t.instance_eval { foo = 'foo' }
>
> Ruby will always see the above as a local variable declaration.
> There is no way around that.
>
> > I also know that t.instance_eval { @foo => 'foo' } would work in this
> > case.  However, I'm trying to set a Rails attribute, so I have to go
> > through the method accessor.
>
> You've showed one way to handle it.  Another is the use
> write_attribute(), if we are talking about ActiveRecord.
>
> James Edward Gray II
>
>

Can I call pass in an object to instance_eval?  Let me show you the
full class...


class ScenarioGenerator
  def initialize
    @rules = []
  end

  def add_rule(&r)
    @rules << r
  end

  def generate
    s = Scenario.new
    num_players = 0
    @rules.each do |r|
      r.call(s)
    end

    s.create_players(num_players) if num_players > 0
    s
  end
end

The reason I went to r.call(s) is so that I can do
g = ScenarioGenerator.new
g.add_rule { |s| s.sb = 200 }

s then becomes the Scenario that I created.

However I want to be able to modify num_players with a rule, so I need
instance_eval.  I still need to be able to pass in the Scenario object
though.  How could I do that?

Pat