How to get only class name without namespace

There is a class like this.

module Foo
  class Bar
  end
end

And I want to get the class name of Bar without Foo.

bar = Foo::Bar.new
bar.class.to_s.match('::(.+)$'){ $1 }

I could get the class name by this code, but I don't think this is a best way to get it.

Is there better way to get the name of class without namespace?

If you are using Rails, you can actually use the demodulize method on the String class. http://apidock.com/rails/String/demodulize

bar.class.name.demodulize

The canonical way to do this is to invoke Object#class and Module#name. For example:

bar.class.name.split('::').last
#=> "Bar"

I believe this would work fine too:

module Foo
  class Bar
  end
end

bar = Foo::Bar.new

print bar.class.to_s.split('::').last

This would result in

Bar

I also believe it would be a bit faster than the regular expression evaluation, but I'm not sure about this and I haven't performed a benchmark.

Suppose we have the following module Foo:

module Foo
  class Bar
  end
  class Tar
  end
  module Goo
    class Bar
    end
  end
end

If you don't know what classes are contained in Foo, you might do the following:

a = ObjectSpace.each_object(Class).with_object([]) { |k,a|
      a << k if k.to_s.start_with?("Foo::") }
  #=> [Foo::Tar, Foo::Goo::Bar, Foo::Bar]

See ObjectSpace::each_object.

You can then do what you wish with the array a. Perhaps you want to narrow this to clases whose names end with "Bar":

b = a.select { |k| k.to_s.end_with?("Bar") }
  #=> [Foo::Goo::Bar, Foo::Bar]

If you want the portion of the names that excludes "Foo::" (though I can't imagine why), it's a simple string manipulation:

b.map { |k| k.to_s["Foo::".size..-1] }
  #=> ["Goo::Bar", "Bar"]

or

b.map { |k| k.to_s[/(?<=\AFoo::).*/]
  #=> ["Goo::Bar", "Bar"] }

Note that there is no object Bar or Goo::Bar.