How to instatiate the class by dynamically receiving the class name

Question

I need to create a class but the condition is, I will receive the class name in strings like shown below

 ["IndividualContact", "Legal"].each do |var|
      ind = var.new
    end

Now My expectation is, I need to call

IndividualContact.new and Legal.new but since var is a string variable, it's calling .new on a string like given below

"IndividualContact".new

rather than calling

IndividualContact.new

Is there any way can I call as I expected?

This has been answered before here: https://stackoverflow.com/questions/5924495/how-do-i-create-a-class-instance-from-a-string-name-in-ruby — Sixty4Bit, Jun 13 '18 at 13:37
@Sixty4Bit the mentioned answer is unrelated since it uses the method that is not existing in Ruby. — Aleksei Matiushkin, Jun 13 '18 at 13:42
@mudasobwa it uses const_get just as your answer does. How is that not a part of Ruby? Look at the second example. — Sixty4Bit, Jun 13 '18 at 13:45

Aleksei Matiushkin · Accepted Answer · 2018-06-13T14:13:43.210

3

Use Module#const_get (assuming these classes are already defined in the global namespace):

%w|IndividualContact Legal|.map do |klazz|
  Kernel.const_get(klazz).new
end

The code above will return an array containing two instances: one instance of IndividualContact and one of Legal.

edited Jun 13 '18 at 14:13

answered Jun 13 '18 at 13:33

You would not need to use const_get with your code because you are passing in constants. If you were passing in Strings then this would work. – Sixty4Bit Jun 13 '18 at 13:37
1

@Sixty4Bit excuse me? I am passing strings. – Aleksei Matiushkin Jun 13 '18 at 13:41
perfect, works perfectly! – Rajagopalan Jun 13 '18 at 13:42
Apologies. Missed the %w. – Sixty4Bit Jun 13 '18 at 13:42
might mention that these classes need to be defined in the current context because when I read the title and this fragment *"I need to create a class..."* I was a assuming the OP was looking for `Class.new` and `const_set` – engineersmnky Jun 13 '18 at 14:13
@engineersmnky thanks, updated. – Aleksei Matiushkin Jun 13 '18 at 14:13

1 Answers1