Get value of all constants defined in a module

Question

I want to get the values of all the constants defined in a module:

module Letters
  A = 'apple'.freeze
  B = 'boy'.freeze
end

constants gave me the name of the constants:

Letters.constants(false)
#=> [:A, :B]

How do I get an array of their values, i.e. ["apple", "boy"]?

We are using third party library that requires to use strings. — Sahil Rally, Jan 22 '18 at 16:28
Long story :) https://stackoverflow.com/questions/1217088/what-does-mapname-mean-in-ruby — Sergio Tulentsev, Jan 22 '18 at 16:32
Just noticed and realised that it gives [:A, :B] and not [:a,:b] , I mean its name of constant and not its value. I need value — Sahil Rally, Jan 22 '18 at 16:46
@stefan We are using Kwalify library to validate YAML file. One o the keys can take list of String values as Kwalify has type str for string. We are loading these values from a module of constants defined in some class. — Sahil Rally, Jan 22 '18 at 16:51
@mudasobwa that's going to be a steep learning curve for the OP ;-) — Stefan, Jan 22 '18 at 16:53
@mudasobwa . **awesome**. Exactly what I required, Could you give me references to read to understand its real meaning. — Sahil Rally, Jan 22 '18 at 16:53
@Stefan Yes you are right , I realised it later since I used same name of constants and its values . I have modified it now. — Sahil Rally, Jan 22 '18 at 17:01

Sahil Rally · Answer 1 · 2018-01-23T08:39:11.963

16

In order to do this use map

Letters.constants(false).map &Letters.method(:const_get)

this will return ["a","b"]

Second way :

Letters.constants(false).map { |c| Letters.const_get c }

Thanks @mudasobwa and Sagar Pandya for their answer.

edited Jan 23 '18 at 08:39

answered Jan 22 '18 at 16:33

Sahil Rally

3

Some may prefer `Letters.constants(false).map { |c| Letters.const_get c }` – Sagar Pandya Jan 22 '18 at 17:03
1

You edited your answer to replace what you had initially with @mudasobwa's comment (*verbatim!*). Considering that mudsie chose not to submit an answer, there's nothing wrong with that (it's a good answer, so we need to see it), but don't you think you should have attributed it to him? – Cary Swoveland Jan 23 '18 at 05:00
@CarySwoveland Absolutely ! – Sahil Rally Jan 23 '18 at 08:23

1 Answers1