How to extract the class names?

Ruby
1

I have written a code as below :

module A
module B
class B2
class B1Error < Exception ;end
class B2_inner
$a = Module.constants
end
end
end
end

$a - Module.constants

=> [:B1Error, :B2_inner, :B2, :B]

But now I want only the class names… How to do so? means I want only
the below:

[:B1Error, :B2_inner, :B2]

2

Module.constants.select { |const| Module.const_get(const).is_a? Class }

Don’t have ruby so this might contain typos.

John

3

John W Higgins wrote in post #1119210:

Module.constants.select { |const| Module.const_get(const).is_a? Class }

Don’t have ruby so this might contain typos.

I am getting error… :frowning:

module A
module B
class B2
class B1Error < Exception ;end
class B2_inner
$a = Module.constants
end
end
end
end

($a - Module.constants).select { |const| Module.const_get(const).is_a?
Class }

=>

~> -:12:in `const_get’: uninitialized constant Module::B1Error

(NameError)

~> from -:12:in `block in ’

~> from -:12:in `select’

~> from -:12:in `’

4

This would work

module A
  module B
    class B2
      class B1Error < Exception ;end
      class B2_inner
      end
    end
  end
end

def nested_classes(root)
  [].tap do |klasses|
    root.constants(false).map do |name|
      if (value = root.const_get(name)).is_a?(Module)
        klasses << value if value.is_a?(Class)
        klasses.concat(nested_classes(value))
      end
    end
  end
end

p nested_classes(A)
# => [A::B::B2, A::B::B2::B1Error, A::B::B2::B2_inner]

Note however that the nesting does not necessarily reflect nested
namespaces.

5

On Tue, Aug 20, 2013 at 11:32 PM, Xavier N. [email protected] wrote:

    root.constants(false).map do |name|

That #map should be an #each, it works but it is unnecessary (comes from
editing a previous attempt).

6

Xavier N. wrote in post #1119213:

That #map should be an #each, it works but it is unnecessary (comes from
editing a previous attempt).

Thanks for your reply:

I did it as below:

module A
module B
class B2
class B1Error < Exception ;$b= Module.nesting ; end
class B2_inner
$a = Module.nesting
end
end
end
end

($a | $b)

=> [A::b::B2::B2_inner, A::b::B2, A::B, A, A::b::B2::B1Error]

($a | $b).map{|e| e.respond_to?(:superclass)}

=> [true, true, false, false, true]

($a | $b).select{|e| e.respond_to?(:superclass)}

=> [A::b::B2::B2_inner, A::b::B2, A::b::B2::B1Error]

Is my approach also acceptable ?