Setting Attributes using Hash in RUby

Question

I'm currently completely stuck on a school problem and figured I'd reach out for some guidance.

Define a class named User. Its initialize method should take a Hash as an argument. We'll name the argument config and set a default value for the argument to an empty Hash:

class User
  def initialize(config = {})
  end
end

This config = {} the syntax supplies a "default argument" for initialize. If someone initializes a User instance without a config argument, the config variable in the method will automatically be set to the default we gave it--an empty Hash.

The config argument should be used to set any of the following attributes on a user: name, email, bio, age, and sex. If an attribute is not provided in the Hash argument, the initialize method should default it to a value to "n/a". For example:

class User
  def initialize(config = {})
    @name = config[:name] || "n/a"
    @email = config[:email] || "n/a"
    ...
  end
end

Setting default values is a very common task in Ruby. A basic way to do this is by using the || assignment operator, which means "or". Consider the following examples:

a = 3
a = a || 6
a #=> 3
b = b || 9
b #=> 9

Decode the logic in the conditional assignments above.

We'll also need to access the instance variables set in our initialize method. To do this, we can use the attr_accessor method declaration. The attr_accessor method also lets us declare multiple attributes on one line. For example:

class User
  attr_accessor :name, :email

  def initialize(config = {})
    @name = config[:name] || "n/a"
    @email = config[:email] || "n/a"
    # ...
  end
end

Finish writing the User class and initialize method to handle all of the required attributes.

I am entirely lost at this point. Thanks in advance.

Just add all required attributes to the argument list of attr_accessor and add a line for each required attribute following the existing pattern to the initialize. Or do I miss something? — spickermann
what exactly are you confused about? how to add attributes to a class? are you confused on the attr_accessor does? what are the other requirements for the assignment? because it looks like its already done all you would have to do is add the rest of the attributes to the users class. — Zach Tuttle

Kathryn Kathryn · Accepted Answer · 2017-06-08T06:34:53

It looks as if you've copied your assignment directly. I'm not going to do the work for you, but I will give you some hints on a few lines of code:

def initialize(config = {})

This is using a default parameter value while defining the method. If the user doesn't provide a config hash, the method will use an empty hash by default.

@name = config[:name] || "n/a"

This statement is using || for flow control. If config[:name] is set, the value is assigned to @name. Otherwise, it defaults to "n/a".

attr_accessor :name, :email

This is a shortcut to create getters and setters for :name and :email. It looks like your assignment is to add bio, age, and sex as instance variables and set them up with appropriate defaults.

Setting Attributes using Hash in RUby

1 Answers