如何在 Ruby 中单行初始化多个数组？

Question

I'm trying to do some calculations and get the groups and departments array from there. but if I'm returning it like this [], [] It is giving error, while if I return it like [[],[]] it is working fine but in the later case, 3 arrays will get initialize which I want to avoid? Is there any better way to do it using 2 array itself?

    def fetch_group_dept_values
      if condition
        [1,2,3,], [4,5]
      else  
        [9,15], [10,11]
      end
    end

    groups, departments = fetch_group_dept_values 

Answer 1

if I return it like [[],[]] it is working fine but in the later case, 3 arrays will get initialize which I want to avoid?

It cannot be avoided because a method can only return a single object.

So wrapping the objects in [...] is just fine:

def fetch_group_dept_values
  if condition
    [[1, 2, 3,], [4, 5]]
  else  
    [[9, 15], [10, 11]]
  end
end

The overhead of creating a (small) extra array is negligible.

However, you could avoid the outer array by yielding the values instead of returning them:

def fetch_group_dept_values
  if condition
    yield [1, 2, 3,], [4, 5]
  else  
    yield [9, 15], [10, 11]
  end
end

And call it via:

fetch_group_dept_values do |groups, departments|
  # ...
end

Answer 2

Use return in front,

   def fetch_group_dept_values
      if condition
        return [1,2,3,], [4,5]
      else  
        return [9,15], [10,11]
      end
    end

    groups, departments = fetch_group_dept_values