Question

I’m using a library that lays its library out like this:

module Lib
  class A; end
  class B; end
  ...
end

I know that I can use send on an object to “call” a method known only at runtime (e.g., foo.send(:bar, :baz_param=>42). How can I do this at the class level?

In other words, I suspect there’s a way to write something like this:

label = :Klass
MyModule.some_method(label).new

that executes, in effect, as:

MyModule::Klass.new

Am I right?

Answer 1

As soon as I posted the question, I had a brainwave:

const_get

Class names are treated as constants, and the method is defined for all modules, too, so the lookup scope can be restricted to that module only. Just remember to get the capitalization right:

MyModule.const_get(:Klass).new # => #<Klass:> #CORRECT

MyModule.const_get(:klass).new # => NameError: wrong constant name