Intro to Hashes Lab

Learning Goals

• Build simple hashes.

Introduction

It's time to practice what we've learned about Ruby hashes. In this lab, your task is to implement a set of three methods. Each method will require you to complete some basic hash creation.

Instructions

Code your solutions for the following four methods in the lib/intro_to_ruby_hashes_lab.rb file.

1. Implement a method called new_hash that creates and returns a new, empty hash.

2. Implement a method called my_hash that returns a valid hash. This hash should have at least one key/value pair of your choice.

3. Implement a method called pioneer that returns a hash. This hash should have a key that is a symbol :name and whose value is a string, 'Grace Hopper'.

4. Implement a method called id_hash_generator that takes in one parameter, an integer. This method should create and return a hash with a key :id with the integer as the value.

Try your best to solve these. Use learn and follow the test suite messages as you work through your solution and learn submit when you're finished with your work. Check out the walkthrough below if you get stuck.

Solving this Lab

The four methods we'll be working in are already provided in lib/intro_to_ruby_hashes.rb, so all we need to do is write the implementation for each.

The first method, new_hash, should return a new, empty hash. The most direct way to do this is to write a hash in its implicit form:

def new_hash
  {}
end

Alternatively, we could explicitly create a new Hash:

def new_hash
  Hash.new
end

But we don't see this as often.

When first learning to work with hashes, it is common to think we always need to assign it to a variable, so your solution might look like this:

def new_hash
  hash = {}
  hash
end

Or even this:

def new_hash
  hash = {}
end

While both of these are valid code and return an empty hash, the variable is not needed. All that matters is what gets returned. Because Ruby methods use implicit return, when we create a hash using {}, we can return that directly.

For the second method, my_hash, we will also return a hash. This hash must have some key/value pair included. Your choice.

def my_hash
  { :favorite_color => "blue" }
end

When using symbols for keys, we can write key/value pairs as seen above, or with the alternative syntax:

def my_hash
  { favorite_color: "blue" }
end

For the third method, pioneer, the task is the same as the previous method. Except this time, the key should be :name and the value should be Grace Hopper:

def pioneer
  { name: "Grace Hopper" }
end

In the final method, id_hash_generator, we need to use a parameter. This parameter should be assigned to the :id key in a hash, and the hash should be returned. Similar to the previous methods, we return a hash, giving it one key. The value will be set to whatever the parameter is:

def id_hash_generator(number)
  { id: number }
end

Conclusion

Hashes are an essential data type that we will use frequently. Now that you've practiced the basics of creating hashes, we will practice reading and updating them.

Resources

• What is a Hash in Ruby?
• Ruby Documentation on Hashes