Default Values: Meal Choice Lab

Learning Goals

Define a method that takes in required and optional arguments
Use puts to output a string
Define a return value

Introduction

We've demonstrated the basics of defining methods, printing output, and returning values. Let's combine the concepts we've shown you to create a "Meal Choice" in our Ruby program.

Instructions

We're attending a wedding and the newlyweds-to-be want to know what types of food they should provide at the banquet. Define a method named meal_choice that has three parameters:

Two required parameters for vegetables. Ex: veg1 and veg2
And an optional parameter for protein with a default value of tofu

This method will serve a couple of purposes - we want to output a two messages and return one of the messages as a string.

The first message will always be the same:

"What a nutritious meal!"

The second message is structured to include all three parameters like so:

"A plate of #{protein} with #{veg1} and #{veg2}."

If the meal_choice method was run with carrots, string beans, and lentils:

2.6.1 :001 > meal_choice('carrots', 'string beans', 'lentils')
What a nutritious meal!
A plate of lentils with carrots and string beans.
 => "A plate of lentils with carrots and string beans."

In addition, if we were to leave off the third parameter, lentils, we would expect the following:

2.6.1 :002 > meal_choice('carrots', 'string beans')
What a nutritious meal!
A plate of tofu with carrots and string beans.
 => "A plate of tofu with carrots and string beans."

Notice above that the return value shown on last line is the same message as what is output. You will need to compose this message in a way that you can output it and return it.

Write your solution in the file lib/meal_choice.rb using the information provided below.

Solving this Lab

Whether you're omnivorous, vegetarian, or vegan, you're going to be eating a nutritious meal!

First, we should build out the empty method with veg1 and veg2 as required parameters, and protein as an optional parameter with the default value of tofu:

def meal_choice(veg1, veg2, protein = 'tofu')

end

For the implementation, the first message is always the same, so we can handle that with a puts statement:

def meal_choice(veg1, veg2, protein = 'tofu')
  puts "What a nutritious meal!"
end

Now, for the second message, we could do something similar:

def meal_choice(veg1, veg2, protein = 'tofu')
  puts "What a nutritious meal!"
  puts "A plate of #{protein} with #{veg1} and #{veg2}."
end

With this, we've output all the messages and solved the first test in this lab. There is still something else needed, though - remember that puts statements return nil:

2.6.1 :003 > puts "Hello!"
Hello!
 => nil

Similarly, if we run the current version of meal_choice, we will get the following:

2.6.1 :001 > meal_choice('carrots', 'string beans', 'chicken')
What a nutritious meal!
A plate of chicken with carrots and string beans.
 => nil

Instead of ending the method with a puts, we will need to add an additional line specifying what to return. One possible solution:

def meal_choice(veg1, veg2, protein = 'tofu')
  puts "What a nutritious meal!"
  puts "A plate of #{protein} with #{veg1} and #{veg2}."
  "A plate of #{protein} with #{veg1} and #{veg2}."
end

This works, but this code is a bit repetitive. We are creating our custom message twice. Instead, we might consider assigning the message to a variable, outputting the variable, then returning it:

def meal_choice(veg1, veg2, protein = 'tofu')
  puts "What a nutritious meal!"
  meal = "A plate of #{protein} with #{veg1} and #{veg2}."
  puts meal
  meal
end

Ruby implicitly returns the value of the final expression, in this case, meal. We can include an explicit return:

def meal_choice(veg1, veg2, protein = 'tofu')
  puts "What a nutritious meal!"
  meal = "A plate of #{protein} with #{veg1} and #{veg2}."
  puts meal
  return meal
end

But it is not necessary here.

Conclusion