Should the Applicant class “require 'mad_skills'” or “include 'mad_skills'”?
-
05-07-2019 - |
Question
Also, what does "self.send attr
" do? Is attr
assumed to be a private instance variable of the ActiveEngineer class? Are there any other issues with this code in terms of Ruby logic?
class Applicant < ActiveEngineer
require 'ruby'
require 'mad_skills'
require 'oo_design'
require 'mysql'
validates :bachelors_degree
def qualified?
[:smart, :highly_productive, :curious, :driven, :team_player ].all? do
|attr|
self.send attr
end
end
end
class Employer
include TopTalent
has_millions :subscribers, :include=>:mostly_women
has_many :profits, :revenue
has_many :recent_press, :through=>[:today_show, :good_morning_america,
:new_york_times, :oprah_magazine]
belongs_to :south_park_sf
has_many :employees, :limit=>10
def apply(you)
unless you.build_successful_startups
raise "Not wanted"
end
unless you.enjoy_working_at_scale
raise "Don't bother"
end
end
def work
with small_team do
our_offerings.extend you
subscribers.send :thrill
[:scaling, :recommendation_engines, : ].each do |challenge|
assert intellectual_challenges.include? challenge
end
%w(analytics ui collaborative_filtering scraping).each{|task|
task.build }
end
end
end
def to_apply
include CoverLetter
include Resume
end
Solution
require 'mad_skills'
loads the code in mad_skills.rb (or it loads mad_skills.so/.dll depending on which one exists). You need to require a file before being able to use classes, methods etc. defined in that file (though in rails files are automatically loaded when trying to access classes that have the same name as the file). Putting require inside a class definition, does not change its behaviour at all (i.e. putting it at the top of the file would not make a difference).
include MadSkills
takes the module MadSkills
and includes it into Applicant
's inheritance chain, i.e. it makes all the methods in MadSkills
available to instances of Applicant
.
self.send attr
executes the method with the name specified in attr on self and returns its return value. E.g. attr = "hello"; self.send(attr)
will be the same as self.hello
. In this case it executes the methods smart
, highly_productive
, curious
, driven
, and team_player
and checks that all of them return true.