CODEWITHSUNDEEP
ruby
Just a learner
Just a learner

Reputation: 28592

Why doesn't Ruby have an is_an? method?

Why doesn't Ruby have an is_an? method? For example:

[].is_an? Array?

Upvotes: 3

Views: 1172

Answers (6)

Joshua Pinter
Joshua Pinter

Reputation: 47551

Create an is_an? alias initializer.

We ended up creating a little initializer to add this alias into our project, since we are mostly English speakers and prefer the grammatical correctness that is_an? affords:

config/initializers/is_an.rb

# Aliases `is_an?` to `is_a?` so we correctly use `is_an?( Array )` instead of `is_a?( Array )`
#
# Surprisingly, not in the Ruby core, but it almost made it into the Rails core.
# For the discussion, see https://github.com/rails/rails/pull/6243
#
class Object
  alias is_an? is_a?
end

Upvotes: 2

lucas
lucas

Reputation: 1151

Rails maintainer Andrew White gave the following reason:

it's purely an English language idiosyncrasy and since many (most?) Ruby programmers do not have English as their primary language they may not be aware of it, leading to confusion.

See this pull request for the full discussion on the topic: Improved readability for object introspection (is_a?)

Maybe it would get added if someone opened the same pull request in the Ruby repository!

Upvotes: 3

fyr
fyr

Reputation: 20869

You might consider using is_a? instead eg.:

if [].is_a? Array
   puts "Array"
end

If you really need to have is_an? you might also achieve it with an alias:

class Object
  alias :is_an? :is_a?
end

if [].is_an? Array
   puts "Array"
end

Upvotes: 7

aarona
aarona

Reputation: 37324

I think the method you are looking for is kind_of?

See here:

http://ruby-doc.org/core-1.9.3/Object.html#method-i-kind_of-3F

Upvotes: 5

David Grayson
David Grayson

Reputation: 87476

Ruby has is_a? already which does what you want. You could make is_an? in 3 lines of code if you want but I think it's a bad idea. There are too many synonyms already in the standard Ruby library that make it harder than necessary to learn. I just recently learned that Enumerable's map and collect are the same.

Upvotes: 2

j_mcnally
j_mcnally

Reputation: 6968

Try http://ruby-doc.org/core-1.9.3/Object.html#method-i-is_a-3F

Upvotes: 0

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