Find classes available in a Module

Question

I have a module MyModule. I dynamically load classes into it. How can I get a list of the classes defined within its namespace?

Example:

def load_plugins   Dir.glob(File.dirname(__FILE__) + '/plugins/*.rb') do |f|     MyModule.class_eval File.read(f)   end    # now how can I find the new classes I've loaded into MyModule? end 

I should say that each f contains something like "class Foo; end".

You can also think of it like this: in Rails, how could I programatically find all classes defined within the ActiveRecord module?

Answer 1

Classes are accessed through constants. Classes defined within a module are listed as constants in that module. So you just need to choose the constants that refer to classes.

MyModule.constants.select {|c| MyModule.const_get(c).is_a? Class} 

Answer 2

If you're on rails, you need to access the constants first for them to show up, because they're lazyly loaded.

MyModule::NotAClass = "not a class"  MyModule.constants => [:NotAClass]  MyModule::AClass => :AClass # Access class for it to be autoloaded  MyModule.constants => [:AClass, :NotAClass]  # Now, select the constants which are class instances  MyModule.constants         .map(&MyModule.method(:const_get))         .select { |constant| constant.is_a? Class}    => [MyModule::AClass]**