README.md

Usage

Normal

person = Person.new('Jo', 'Bloggs')
    
HumanName.new(person).full_name
> "Joe Bloggs"

Specify name attributes

person = Person.new(title: 'Mr', first: 'Jo', last: 'Bloggs')
    
HumanName.new(person, :title, :first, :last).full_name
> "Mr Joe Bloggs"

Interpolation

person = Person.new('Jo', 'Bloggs')
    
string = "My name is #{HumanName.new(person)}"
> "My name is Joe Bloggs"

Splat the arguments in from an array

names = [ :first, :last ]
name = HumanName.new(person, *names)

gistfile1.rb

class Person
  attr_reader :first_name, :last_name
  
  def initialize(first_name, last_name)
    @first_name, @last_name = first_name, last_name
  end
  
  def full_name
    HumanName.new(self, :title, :first_name, :last_name)
  end
end

human_name.rb

class HumanName
  attr_reader :nameable, :name_attributes

  def initialize(nameable, *name_attributes)
    @nameable        = nameable
    @name_attributes = name_attributes
  end

  def full_name
    names.join(" ")
  end

  def names
    name_attributes.map do |attribute|
      unless nameable.respond_to?(attribute)
        raise ArgumentError.new("#{nameable.class} does not respond to `#{attribute}`")
      end

      nameable.send(attribute)
    end
  end

  def name_attributes
    @name_attributes.empty? ? defaults : @name_attributes
  end

  def to_s
    full_name
  end

  private

  def defaults
    [ :first_name, :last_name ]
  end
end

human_name_test.rb

require "minitest/autorun"
require "minitest/pride"
require "mocha"

require_relative "../../app/models/human_name"

describe HumanName do

  it "must output the first and last name by default" do
    person = stub(first_name: 'Jo', last_name: 'Bloggs')

    name = HumanName.new(person)
    name.full_name.must_equal "Jo Bloggs"
  end

  it "must interpolate easily" do
    person = stub(first_name: 'Jo', last_name: 'Bloggs')

    string = "#{HumanName.new(person)}"
    string.must_equal "Jo Bloggs"
  end

  it "must allow specifying which attributes to use" do
    person = stub(first: 'Jo', last: 'Bloggs')

    name = HumanName.new(person, :first, :last)
    name.full_name.must_equal "Jo Bloggs"
  end

  it "must raise an ArgumentError if incorrect attributes are supplied" do
    person = Object.new

    name = HumanName.new(person, :i_dont_exist)
    proc { name.full_name }.must_raise ArgumentError
  end
end