Method naming conventions (? and ! suffixes) in Ruby - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to define a method that checks if a number is even using the correct naming convention.

Ruby

def even[1](number)
  number % 2 == 0
end

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

A_test

B!

C_check

D?

Attempts:

3 left

💡 Hint

Common Mistakes

Using '!' instead of '?' for a method that returns a boolean.

Adding arbitrary suffixes like '_check' or '_test' which are not Ruby conventions.

In Ruby, methods that return a boolean value often end with a question mark (?).

2fill in blank

medium

Complete the code to define a method that modifies a string in place, following Ruby naming conventions.

Ruby

def capitalize[1](str)
  str.capitalize!
end

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

A!

B?

C_inplace

D_modify

Attempts:

3 left

💡 Hint

Common Mistakes

Using '?' instead of '!' for methods that modify objects.

Adding suffixes like '_inplace' which are not standard Ruby conventions.

In Ruby, methods that modify the object they are called on usually end with an exclamation mark (!).

3fill in blank

hard

Fix the error in the method name to follow Ruby conventions for a method that returns a boolean.

Ruby

def valid_email[1](email)
  email.include?('@')
end

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

A!

B_check

C?

D_valid

Attempts:

3 left

💡 Hint

Common Mistakes

Using '!' for boolean methods.

Using arbitrary suffixes like '_check' or '_valid'.

Boolean methods in Ruby should end with a question mark (?).

4fill in blank

hard

Complete the code to define a method that modifies an array in place and returns a boolean indicating success.

Ruby

def add_element[1](array, element)
  array << element
  true
end

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

A!

B?

D_modify

Attempts:

3 left

💡 Hint

Common Mistakes

Adding '?' after the parameter list which is invalid syntax.

Not using '!' for methods that modify objects.

Methods that modify objects end with '!' and the '?' is not used here because the method returns true explicitly.

5fill in blank

hard

Fill both blanks to define a method that checks if a string is empty and modifies it if not, following Ruby conventions.

Ruby

def process_string[1](str)
  if str.empty[2]
    false
  else
    str.upcase!
    true
  end
end

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

A?

B!

Attempts:

3 left

💡 Hint

Common Mistakes

Using '!' instead of '?' for boolean methods.

Adding suffixes after the parameter list which is invalid.

The method name ends with '?', no suffix after parameters, and 'empty?' is a Ruby method that ends with '?'.

Practice

1. Which method name follows Ruby convention for a method that returns a boolean value?
? is used at the end of method names that return true or false.

easy

A. save

B. update!

C. calculate

D. valid?

Solution

1. Step 1: Understand the meaning of ? suffix

   In Ruby, methods ending with ? return true or false, indicating a boolean check.

2. Step 2: Identify the method that returns a boolean

   Among the options, valid? clearly suggests a boolean check, while others do not.

3. Final Answer:

   valid? -> Option D

4. Quick Check:

   Boolean methods end with ? = valid? [OK]

Hint: Boolean methods end with ? to show true/false result [OK]

Common Mistakes:

• Confusing ! with ? suffix
• Using ? for methods that modify objects
• Not using ? for boolean-returning methods

2. Which of the following method names is correctly written to indicate it modifies the object in Ruby?

easy

A. delete

B. delete!

C. delete?

D. deleted

Solution

1. Step 1: Understand the meaning of ! suffix

   In Ruby, methods ending with ! usually modify the object or perform a 'dangerous' action.

2. Step 2: Identify the method that modifies the object

   delete! clearly indicates modification, while delete may not, and delete? suggests a boolean check.

3. Final Answer:

   delete! -> Option B

4. Quick Check:

   Modification methods end with ! = delete! [OK]

Hint: Use ! for methods that change the object [OK]

Common Mistakes:

• Using ? instead of ! for modifying methods
• Not adding ! for dangerous methods
• Confusing method names without suffixes

3. What will be the output of this Ruby code?

class User
  def active?
    true
  end

  def deactivate!
    @active = false
    "User deactivated"
  end
end

user = User.new
puts user.active?
puts user.deactivate!
puts user.active?

medium

A. true
User deactivated
true

B. true
User deactivated
false

C. false
User deactivated
false

D. true
User deactivated
nil

Solution

1. Step 1: Analyze the active? method

   This method always returns true because it returns the literal true without checking any variable.

2. Step 2: Analyze the deactivate! method and second active? call

   deactivate! sets @active = false but active? does not use @active, so it still returns true.

3. Final Answer:

   true User deactivated true -> Option A

4. Quick Check:

   active? returns true always = true User deactivated true [OK]

Hint: Check if boolean method uses instance variables or fixed return [OK]

Common Mistakes:

• Assuming deactivate! changes active? output
• Confusing method side effects
• Ignoring method return values

4. Identify the error in this Ruby method definition:

def save?
  # saves the object
  puts "Saving..."
  true
end

What is wrong with this method name?

medium

A. Method name cannot contain ?

B. Method should end with ! instead of ?

C. Method ends with ? but performs an action, not a boolean check

D. No error, method is correct

Solution

1. Step 1: Understand the meaning of ? suffix

   Methods ending with ? should return true or false and not perform side effects like saving.

2. Step 2: Analyze the method behavior

   This method prints "Saving..." which is a side effect, so it should not end with ?.

3. Final Answer:

   Method ends with ? but performs an action, not a boolean check -> Option C

4. Quick Check:

   Methods with ? should not have side effects [OK]

Hint: ? means boolean check, not side effects [OK]

Common Mistakes:

• Using ? for methods that change state
• Ignoring method side effects
• Confusing ! and ? suffix meanings

5. You want to write a Ruby method that checks if a string is empty and also a method that clears the string content. Which method names follow Ruby conventions?

hard

A. empty? and clear!

B. empty! and clear?

C. empty and clear!

D. empty? and clear

Solution

1. Step 1: Identify boolean check method

   The method checking if a string is empty should return true or false, so it should end with ?, e.g., empty?.

2. Step 2: Identify modifying method

   The method that clears the string modifies it, so it should end with !, e.g., clear!.

3. Final Answer:

   empty? and clear! -> Option A

4. Quick Check:

   Boolean check ends with ?; modifying method ends with ! [OK]

Hint: Boolean methods end with ?; modifying methods end with ! [OK]

Common Mistakes:

• Swapping ? and ! suffixes
• Not using suffixes for clarity
• Using no suffix for modifying methods