Can you call an instance method when assigning a class variable in Ruby?

Question

I have some methods that contain lots of different combinations of the same logic. To clean it up, I would like to define each test just once.

class Sentence < ApplicationRecord

#Gathers options hash for sentence
def options
    { 
        pronoun: subject.pronoun,
        ...
        }
end

#gives auxiliary verb based on sentence options 
def aux
    third_person = ["he", "she", "it"].include?(options[:pronoun])

    aux = "does" if third_person #just an example 
    ...
end
...

This works fine, but I am trying to pull this out of the aux method to use in other methods.

#this works
@@third_person = ["he", "she", "it"].include?("he")
#this says that there is no options method
@@third_person = ["he", "she", "it"].include?(options[:pronoun])

Does anyone know, what I'm missing?

When we're talking about "cleaning things up", one thing you want to pay careful attention to is declaring unchanging, but throw-away arrays inside methods like this. Use a constant like PREFIXES = %w[ he she it ] and then use that array over and over. You could also use a regular expression if there's some ambiguity or performance concerns. Likewise, returning a temporary hash that's used once is very inefficient, especially if the hash never changes. — tadman
– tadman, Commented Sep 29, 2016 at 15:27
The context of the test code isn't clear. Where are you running that? Also why are you declaring class-style @@ variables? — tadman
– tadman, Commented Sep 29, 2016 at 15:30
I agree with @tadman that you should separate the pronouns to constant variable. Also use freeze method so it cannot be modified. PREFIXES = %w(he she it).freeze — jan.zikan
– jan.zikan, Commented Sep 29, 2016 at 15:33
Ok, cool no problem with the constant because it won't be changing. I think I'm a bit confused with the class variable though. It doesn't seem like its capable of doin what I want. I have an instance of sentence. The options method gets the options for that instance. I want to define a test that uses an instance option once and have access to it from the other instance methods. I guess another instance method would be the way to go? — Michael Parton
– Michael Parton, Commented Sep 29, 2016 at 15:44

jan.zikan · Accepted Answer · 2016-09-29 15:30:24Z

1

You are not calling the instance method options on instance of class Sentence.

You have to call it this way:

sentence = Sentence.new
['he', 'she', 'it'].include?(sentence.options[:pronoun])

answered Sep 29, 2016 at 15:30

jan.zikan

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1 Comment

Michael Parton Over a year ago

That's the right answer to my question, but now I realise that I was going about everything the wrong way. Thanks for the quick answers, it helped me rethink my code.

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