Check if module exists in ruby

Question

I'm dynamically defining a module name from an argument passed on the cli, for example "Required::Module::#{ARGV.first}"

Is there any way to check if that module exists? Also, how would I run methods on it not knowing it's exact name?

Answer 1

Check for module existence using the const_get method:

begin
    mod = Required::Module::const_get "ModuleName"
    #It exists
rescue NameError
    #Doesn't exist
end

Answer 2

defined?(Required::Module)

gives "constant" if it exists, and nil if it doesn't.

Update: Sorry, didn't read your question properly.

defined?(eval("Required::Module::"+string))

should give you what you're after.

Answer 3

Use const_defined? for this.

Required::Module.const_defined?(:ModuleName)

returns true or false.