Convert Strings to Class Names in ruby

The conventional way of assigning a name to an anonymous class is as follows.

bub = Class.new do
  def b
    'hi'
  end
end

str = 'Bubba'
Object.const_set(str, bub)

Bubba.is_a?(Class)
  #=> true
Bubba.new.b
  #=> "hi"

Is that what you want to do? If so, as you see, you need to use Module#const_set.

Do you try to use const_get only for a class or it is under a namespace like ModuleA::ModuleB::ClassName?

Also converting a string to a class name makes a new class or assigns the value to it?

I am asking these questions because the answer will affect the method you have to use. Maybe const_set instead of const_get is the correct approach, I don't know.

From the comments you gave it looks like 'String' is just an example and not the value that you literally pass to const_get. The actual value apparently is 'Assignment', is this correct?

When you execute Object.const_get('Assignment') and you receive the uninitialized constant error it indicates that at this point the class Assignment has not been loaded yet.

When you are using Rails then a lot of autoloading takes place if the files are in the right folder and the classes follow the naming conventions. Since you are running a "standalone" ruby script, autoloading does not take place and you will need to load the file yourself.

Adding a line like

require_relative "somepath/assignment"

should work. somepath needs to be adapted to the directory/file layout you have. It will load the file and execute the ruby code in that file. If assignment.rb defines something like

class Assignment
end

Then the const_get will work.

That being said: what is your exact use case for this? Why do you need to dynamically find classes? Also Note that this opens up your app to (an unlikely) potential security issues if you let user input define what classes are loaded.