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How to return multiple values in ruby

ViriCruz on August 29, 2019

You can return multiple values on a method using comma-separated values when you return the data. Check the example below def multiple_values ...
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oinak profile image
Oinak • • Edited

That is a very neat explanation, thanks for sharing!

I see your post is centered on the how and not on the why.

One of the most common errors in ruby is:

NoMethodError: undefined method 'foo' for nil:NilClass

It comes from calling a method on the result of a function that we forgot could return nil.

Usually, when I feel tempted to return mutiple or complex values, I tend to:

A) Return a hash than documents what they are:

  def complex_value
    thing = some_query
    {
      status: (thing ? :ok : :not_found),
      content: thing.something
    } # always responds to [:status] and [:content]
  end
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B) Return an object with a NullObject pattern to avoid nil.something down the line.

class Result
  attr_reader :name, :other
  def initialize(value)
    @name = value ? value.name : 'Not found'
    @price = value ? " $#{value.amount} " : '-'
  end
end

def complex_value
  thing = some_query
  Result.new(thing) # always responds to '.name' and '.price'
end
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I know the example is a bit contrived due to brevity, but I hope it lets my point though.

What do you think?

P.S.: Sandi Metz on this matters

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viricruz profile image
ViriCruz •

Yes, you're right NoMethodError: undefined method 'foo' for nil:NilClass this a very common error in ruby and I understand your point of view. Thanks for sharing your opinions! 😁

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Michael Currin •

Thanks, I was looking for how to return a tuple.

Tip - you can unpack all the variables in one line.

def foo
  return "abc", 2, true
end

a, b, c = foo()
a
# "abc"
b
# 2
c
# true
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