Constant lookup as-if toplevel

ruby-talk
1

I'm evaluating a ruby script against a testing DSL that I wrote. Now I
would have loved to run the scripts at the toplevel, but the
contamination of the Object class makes that infeasible. So I run them
within a Scope object. Basically:

  class Scope < Module

    def initialize
      extend self
    end

    def execute(script, filename)
      eval(script, binding, filename)
    end

  end

My problem arises when a script uses a constant that isn't defined and
the error message looks like this:

  ERROR: NameError uninitialized constant #<Scope:0x7f3cc21e5630>::Foo

I'm trying to find a way to get rid of the `#<Scope:...>::` part. To
the end user it should at least *look* like things are running at
toplevel.

I tried adding to Scope:

  def inspect; ""; end

But that did not work. Any ideas?

2

I ran into this same problem today myself, although attempting something
different. I wanted to stylize a constant name with a bang! Our company's
name happens to be stylized with a bang, so I thought I'd be silly and try
to translate that into Ruby itself (I was inspired by Rainbows!)

So I tried this:

<http://gist.github.com/653850&gt;Which is fine, but when I created classes
within the namespace of my bangmodule, they still inspect without the bang!

I want the bang! Bring on the bang!

···

On Fri, Oct 29, 2010 at 4:06 PM, Intransition <transfire@gmail.com> wrote:

I'm evaluating a ruby script against a testing DSL that I wrote. Now I
would have loved to run the scripts at the toplevel, but the
contamination of the Object class makes that infeasible. So I run them
within a Scope object. Basically:

class Scope < Module

   def initialize
     extend self
   end

   def execute(script, filename)
     eval(script, binding, filename)
   end

end

My problem arises when a script uses a constant that isn't defined and
the error message looks like this:

ERROR: NameError uninitialized constant #<Scope:0x7f3cc21e5630>::Foo

I'm trying to find a way to get rid of the `#<Scope:...>::` part. To
the end user it should at least *look* like things are running at
toplevel.

I tried adding to Scope:

def inspect; ""; end

But that did not work. Any ideas?

--
Tony Arcieri
Medioh! A Kudelski Brand

3

Why not add a const_missing() to your Scope class and explicitly lookup
the constant on Object there, which will fail, and so the error will be
as if a top-level constant wasn't found.

···

--
Posted via http://www.ruby-forum.com/.

4

err, that should be:

    class Scope
      def self.const_missing(const)
        Object.const_get(const)
      end
    end

John

···

--
Posted via http://www.ruby-forum.com/.

5

yup

def execute( script, filename )
   eval(script, Module.new.send(:binding), filename)
end
execute( "Foo", "here" )

which gives

here:1:in `execute': uninitialized constant Object::Foo (NameError)

does this suit your needs better?
If this still causes the conflicts you were talking about, I like John's idea.

HTH
R

···

On Sat, Oct 30, 2010 at 12:06 AM, Intransition <transfire@gmail.com> wrote:

--
There are worse things than having people misunderstand your work. A
worse danger is that you will yourself misunderstand your work.
-- Paul Graham

6

Nice. I removed `self.` b/c Scope is a self extended module, and it
looks good.

Thanks.

···

On Oct 31, 12:28 am, John Mair <jrm...@gmail.com> wrote:

err, that should be:

class Scope
  def self\.const\_missing\(const\)
    Object\.const\_get\(const\)
  end
end