Module_eval for dynamic behavior in Ruby - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to define a method dynamically using module_eval.

Ruby

module Greeter
  module_eval do
    def [1]
      "Hello!"
    end
  end
end

class Person
  include Greeter
end

puts Person.new.hello

Drag options to blanks, or click blank then click option'

Agreet

Bwelcome

Csay_hello

Dhello

Attempts:

3 left

💡 Hint

Common Mistakes

Using a method name different from 'hello' causes a NoMethodError.

The method defined dynamically is hello, so calling Person.new.hello works.

2fill in blank

medium

Complete the code to dynamically add a method that returns the given name.

Ruby

module PersonModule
  module_eval do
    def name
      [1]
    end
  end
end

class Person
  include PersonModule
  def initialize(name)
    @name = name
  end
end

puts Person.new("Alice").name

Drag options to blanks, or click blank then click option'

A"Bob"

Bname

C@name

D"Alice"

Attempts:

3 left

💡 Hint

Common Mistakes

Returning a string literal instead of the instance variable.

The method returns the instance variable @name which holds the person's name.

3fill in blank

hard

Fix the error in the code by completing the module_eval string to define a method.

Ruby

module Calculator
  module_eval "def [1](x, y); x + y; end"
end

class MathOps
  include Calculator
end

puts MathOps.new.add(5, 3)

Drag options to blanks, or click blank then click option'

Aadd

Bcalculate

Cplus

Dsum

Attempts:

3 left

💡 Hint

Common Mistakes

Defining a method with a different name than the one called causes NoMethodError.

The method called is add, so the dynamically defined method must be named add.

4fill in blank

hard

Fill both blanks to dynamically define a method that multiplies a number by a factor.

Ruby

module Multiplier
  module_eval do
    def multiply_by_[1](num)
      num [2] [1]
    end
  end
end

class Number
  include Multiplier
end

puts Number.new.multiply_by_3(4)

Drag options to blanks, or click blank then click option'

A3

B*

C+

D-

Attempts:

3 left

💡 Hint

Common Mistakes

Using '+' or '-' instead of '*' for multiplication.

The method name includes the factor '3', and the operation is multiplication '*'.

5fill in blank

hard

Fill all three blanks to dynamically define a method that checks if a number is greater than a threshold.

Ruby

module Checker
  module_eval do
    def greater_than_[1](num)
      num [2] [3]
    end
  end
end

class NumberCheck
  include Checker
end

puts NumberCheck.new.greater_than_10(15)

Drag options to blanks, or click blank then click option'

A10

B>

C<

D==

Attempts:

3 left

💡 Hint

Common Mistakes

Using '<' or '==' instead of '>' for the comparison.

The method name includes '10', the comparison operator is '>', and the threshold is 10.