Try something like Python for-else in Ruby

Trigger

Read Effective Python Memo Item 12 Avoid using else blocks after for and while loops, and wonder how to write it as Ruby. Became.

things to do

a = 4
b = 9
for i in range(2, min(a, b) + 1):
    print('Testing', i)
    if a % i == 0 and b % i == 0:
        print('Not coprime')
        break
    else:
        print('Coprime')

The ʻelse` clause is executed when the loop ends uninterrupted. Sure, it's not intuitive. I'll do this with Ruby.

Consideration

Ignoring the ʻelse` clause, in the case of Ruby,

a = 4
b = 9
(2..[a, b].min).each do |i|
  puts "Testing: #{i}"
  if (a % i).zero? && (b % i).zero?
    puts "Not coprime"
    break
  end
end

It will be. ʻEachreturnsself, so if the iteration ends without break, 2 .. [a, b], that is, the true value is returned, and if break, nil`, that is, A false value is returned.

So, if you connect with ʻand`, it seems to work.

Conclusion

a = 4
b = 9
(2..[a, b].min).each do |i|
  puts "Testing: #{i}"
  if (a % i).zero? && (b % i).zero?
    puts "Not coprime"
    break
  end
end and puts "Coprime"

For the time being, it went well. But it's not beautiful.

To use &&, you need to use puts ("Coprime") or (puts" Coprime ") to strengthen the connection between puts and"Coprime".

bonus

I also thought about how to get Ruby Poku puts out.

Part 1

a = 4
b = 9
puts (2..[a, b].min).each_with_object("Coprime") { |i|
  puts "Testing: #{i}"
  if (a % i).zero? && (b % i).zero?
    break "Not coprime"
  end
}

Part 2

a = 4
b = 9
puts "Coprime".tap {
  (2..[a, b].min).each do |i|
    puts "Testing: #{i}"
    if (a % i).zero? && (b % i).zero?
      break "Not coprime"
    end
  end
}

All are difficult to understand.

As you can see in "Effective Python", it seems best to cut out to a method without doing something like for-else.

def coprime?(a, b)
  (2..[a, b].min).each do |i|
    return false if (a % i).zero? && (b % i).zero?
  end
  true
end

puts coprime?(4, 9) ? "Coprime" : "Not coprime"

Recommended Posts

Try something like Python for-else in Ruby

Something like JS setTimeout in python

Something like tail -f in Python

Do something like Redis transactions in Python

Try gRPC in Python

Try 9 slices in Python

Try LINE Notify in Python

Try implementing Yubaba in Python 3

I want to do something like sort uniq in Python

Do something like a Python interpreter in Visual Studio Code

Try implementing extension method in python