Where did this constant come from?

ruby-talk
1

What's the simplest way to find out where a constant was defined?

I did come up with a way (probably partly ripped off from ActiveSupport), but
it feels convoluted and fragile:

class Module
  def parent_namespace
    parts = self.name.split('::')
    if parts.length > 1
      parts.tap(&:pop).join('::').constantize
    else
      nil
    end
  end
  
  def eldest_ancestor_with_const name
    if const_defined? name
      klass = self
      self.ancestors.each do |ancestor|
        break if klass == Object
        break unless ancestor.const_defined? name
        klass = ancestor
      end
      klass
    else
      nil
    end
  end
  
  def find_const_parent name
    if Object.const_defined? name
      Object
    else
      klass = self
      until klass.const_defined? name
        klass = klass.parent_namespace
        return nil if klass.nil?
      end
      
      klass.eldest_ancestor_with_const(name)
    end
  end
end

2

Hi,

What's the simplest way to find out where a constant was defined?

I did come up with a way (probably partly ripped off from ActiveSupport), but
it feels convoluted and fragile:

class Module
def parent_namespace
   parts = self.name.split('::')
   if parts.length > 1
     parts.tap(&:pop).join('::').constantize
   else
     nil
   end
end

def eldest_ancestor_with_const name
   if const_defined? name
     klass = self
     self.ancestors.each do |ancestor|
       break if klass == Object
       break unless ancestor.const_defined? name
       klass = ancestor
     end
     klass
   else
     nil
   end
end

def find_const_parent name
   if Object.const_defined? name
     Object
   else
     klass = self
     until klass.const_defined? name
       klass = klass.parent_namespace
       return nil if klass.nil?
     end

     klass.eldest_ancestor_with_const(name)
   end
end
end

Something like this:

def find_const_parent(name)
  Object.constants.select do |x|
    x=eval(x)
    [Class,Module].include?(x.class) && x.const_defined?(name)
  end
end

Regards,

Park Heesob

···

2008/8/18 David Masover <ninja@slaphack.com>:

3

David Masover wrote:

What's the simplest way to find out where a constant was defined?

I did come up with a way (probably partly ripped off from
ActiveSupport), but
it feels convoluted and fragile:

just install the gem rak and grep for it.. :slight_smile:

I do this all the time when I have to go into AR..
cd /usr/lib/ruby/gems/1.8/gems/activerecord/lib
rak <constant_name>

done

···

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