Ruby.md

Ruby

Spliting into two variables

first_element, second_element = s_elements.split(",")

Aliasing methods

#!/usr/bin/env ruby
class Microwave
  def on
    puts "Microwave is on"
  end
end

m = Microwave.new
m.on

class Microwave
  alias :old_on1 :on

  def on
    puts "Warning: Do not insert metal objects!"
    old_on1
  end
end

m.on # Message for this specific microwave

class <<m
  alias :old_on2 :on

  def on
    puts "This microwave is weak, add extra time"
    old_on2
  end
end

m.on # Displays extra message
m2 = Microwave.new
m2.on # Does not display extra message

ref

Redirecting standard output

#!/usr/bin/ruby

$stdout = File.open "output.log", "a"

puts "Ruby"
puts "Java"

$stdout.close
$stdout = STDOUT

puts "Python"

ref

Data types

Syntaxe	Type
%w[this will be splitted into an array]	Array
%r[this_is_my_regex]	Regex
%x[ echo 'hi' ]	Will run this as a shell command

ref

TDD (Test Driven Development)

Using Test:

def add_percent(number, percent)
  throw NotImplementedError.new "TODO: add_percent"
  # Wich is simply `number * (1 + (percent / 100))`.
end

describe "add_percent" do
  it "works for some examples" do
    Test.assert_equals(add_percent(1000, 5), 1050.0)
    Test.assert_equals(add_percent(1000, 1.625), 1016.25)
    Test.assert_equals(add_percent(1000, 2), 1020.0)
  end
  it "works for random input" do
    100.times do
      Test.assert_equals(add_percent(rand(100 .. 2000), rand(0 .. 10)), something_sure_to_output_solution)
    end
  end
end

You could also just do (but the error report will be much less clear):

Test.assert_equals(add_percent(1000, 5), 1050.0)
Test.assert_equals(add_percent(1000, 1.625), 1016.25)
Test.assert_equals(add_percent(1000, 2), 1020.0)

Using expect():

def add_percent(number, percent)
  throw NotImplementedError.new "TODO: add_percent"
  # Wich is simply `number * (1 + (percent / 100))`.
end

describe "add_percent" do
  def add_percent(number, percent, expected)
    actual = add_percent(number.dup, percent.dup)
    message = "number = #{number.inspect}\npercent = #{percent.inspect}\n" +
        "actual = #{actual.inspect}\nexpected = #{expected.inspect}"
    expect(actual).to eq(expected), message
  end

  it "works for some examples" do
    do_test(1000, 5, 1050.0)
    do_test(1000, 1.625, 1016.25)
    do_test(1000, 2, 1020.0)
  end
  it "works for random input" do
    100.times do
      do_test(rand(100 .. 2000), rand(0 .. 10), something_sure_to_output_solution)
    end
  end
end

Simpler use case of expect() (but the error report will be less clear):

  describe "Basic Tests" do
    it "Basic Test Cases" do
      expect(add_percent(1000, 5)).to eq 1050.0
      expect(add_percent(1000, 1.625)).to eq 1016.25
      expect(add_percent(1000, 2)).to eq 1020.0
    end
  end