[Solved] Identify the error in this Ruby code: module M def hello "Hello" end end class A include M extend M end puts A.hello puts A.new.hello | Ruby

Ruby - Modules and Mixins

Identify the error in this Ruby code:

module M
  def hello
    "Hello"
  end
end

class A
  include M
  extend M
end

puts A.hello
puts A.new.hello

ANoMethodError on A.new.hello

BNoMethodError on A.hello

CNo error, code runs fine

DSyntaxError due to extend and include

Step-by-Step Solution

Solution:

Step 1: Understand include and extend
include M adds hello as instance method; extend M adds hello as class method.
Step 2: Check method calls
A.new.hello works because of include. A.hello calls class method added by extend.
Step 3: Identify error
Both calls are valid, so no error occurs.
Final Answer:
No error, code runs fine -> Option C
Quick Check:
include adds instance, extend adds class methods [OK]

Quick Trick: include for instance, extend for class methods can coexist [OK]

Common Mistakes:

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