From: Intransition <transfire@...>
Date: 2010-12-13T22:00:55+09:00
Subject: Re: VERSION constant issue



On Nov 25, 12:54 pm, Josh Cheek <josh.ch...@gmail.com> wrote:
> On Thu, Nov 25, 2010 at 7:54 AM, Intransition <transf...@gmail.com> wrote:
> > Ruby's VERSION constant is getting in the way of using #const_missing
> > in my module. Here's some example code:
>
> >  module Foo
> >    def self.const_data
> >      @const_data ||= { 'version' => '1.0.0' }
> >    end
>
> >    def self.const_missing(name)
> >      key = name.to_s.downcase
> >      const_data[key] || super(name)
> >    end
> >  end
>
> >  Foo::VERSION  #=> '1.8.7'
>
> > How can I fix this?
>
> > I tried `remove_const(:VERSION)` at the toplevel but discovered that
> > some Ruby library don't like that (sorry, can't recall which it was
> > off hand).
>
> Here are my results.
>
> module Foo
>   def self.const_data
>     @const_data ||= { 'version' => '1.0.0' }
>   end
>
>   def self.const_missing(name)
>     key = name.to_s.downcase
>     const_data[key] || super(name)
>   end
>
>   VERSION       # => "1.8.7"
>   self::VERSION # => "1.0.0"
>
>   def self.method
>     VERSION     # => "1.8.7"
>   end
>   method
> end
>
> # going back through ruby versions
> # I wasn't able to get these to print
> # the ruby version until 1.7.1
> # thanks, ruby-versions.net :)
> Foo::VERSION # => "1.0.0"
> Foo::VERSION # => "1.0.0"

Hmmm... I haven't been able to quite get the rhyme or reason of the
behavior, but I just got the error again. The code is:

  class TracePoint

    # Access to metadata.
    def self.metadata
      @metadata ||= (
        require 'yaml'
        YAML.load(File.new(File.dirname(__FILE__) + '/
tracepoint.yml'))
      )
    end

    # Access metadata as constants.
    def self.const_missing(name)
      name = name.to_s
      metadata[name] || super(name)
    end

When I use run:

  require 'tracepoint'
  TracePoint::VERSION

I get:

tryit.rb:2: warning: toplevel constant VERSION referenced by
TracePoint::VERSION
"1.8.7"

I got this on both:
  ruby 1.8.7 (2010-01-10 patchlevel 249) [x86_64-linux]
  ruby 1.8.7 (2010-08-16 patchlevel 302) [x86_64-linux]

Ruby 1.9.2 is not a problem.