DSL building patterns in Ruby - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to define a simple DSL method that yields to a block.

Ruby

def my_dsl_method
  [1]
end

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

Ayield

Breturn

Cputs

Dbreak

Attempts:

3 left

💡 Hint

Common Mistakes

Using return instead of yield stops the method without running the block.

Using puts prints text but does not execute the block.

The yield keyword calls the block passed to the method, which is essential in DSLs to execute user-defined code.

2fill in blank

medium

Complete the code to define a DSL method that takes a block and instance_eval's it.

Ruby

def configure
  instance_eval [1]
end

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

A&block

Bblock

Cyield

Dself

Attempts:

3 left

💡 Hint

Common Mistakes

Passing block without & causes an error because block is not defined as a variable.

Using yield here does not work with instance_eval.

The &block syntax passes the block as a Proc object, which instance_eval can execute in the context of the current object.

3fill in blank

hard

Fix the error in the DSL method that tries to store configuration values.

Ruby

class Config
  def initialize
    @settings = {}
  end

  def set(key, value)
    @settings[[1]] = value
  end
end

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

Avalue

Bkey.to_s

Ckey.to_sym

Dself

Attempts:

3 left

💡 Hint

Common Mistakes

Using key.to_s may cause inconsistency if keys are symbols elsewhere.

Using value as a key is incorrect.

Converting the key to a symbol ensures consistent keys in the settings hash, which is a common practice in DSLs.

4fill in blank

hard

Fill both blanks to create a DSL method that stores a block and later calls it with instance_eval.

Ruby

class Builder
  def initialize
    @block = nil
  end

  def define(&[1])
    @block = [2]
  end

  def run
    instance_eval(&@block)
  end
end

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

Ablock

Bproc

Dlambda

Attempts:

3 left

💡 Hint

Common Mistakes

Using different names for the block parameter and the stored variable causes errors.

Using proc or lambda without defining them causes errors.

The method takes a block parameter named block and stores it in @block. Later, instance_eval runs this block in the object's context.

5fill in blank

hard

Fill all three blanks to create a DSL method that builds a hash from keys and values with a condition.

Ruby

def build_hash(items)
  result = { [1] => [2] for [3] in items if [2].length > 3 }
  result
end

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

Aitem

Bvalue

Ckey

Dk

Attempts:

3 left

💡 Hint

Common Mistakes

Using the same variable name for key and value causes confusion.

Not matching the variable names in the condition causes errors.

This code builds a hash where k is the key and value is the value from items. It includes only those where the value's length is greater than 3.