FioFiyo

System Design Cheatsheet

Picking the right architecture = Picking the right battles + Managing trade-offs

Basic Steps

1. Clarify and agree on the scope of the system

• User cases (description of sequences of events that, taken together, lead to a system doing something useful)
  • Who is going to use it?
  • How are they going to use it?

FioFiyo

SELECT authors.id AS "ID",(authors.first_name)|| ' '||(authors.last_name) AS "Full name",COUNT(books.title) AS "Number of Books"
FROM books 
 JOIN authors ON (authors.id = books.author_id)
 GROUP BY authors.id
ORDER BY COUNT(books.title) DESC

FioFiyo

class Barracks
	attr_reader :gold, :food

	def initialize
		@gold = 1000
		@food = 80
	end

	def train_footman
		if can_train_footman?

FioFiyo

require "pry-byebug"

#implement clear values within the loop
def barks_really_loud
	puts "WOOF WOOF WOOF"
end

# create method to evaluate word
def behaviour
# # binding.pry

FioFiyo

# 1.upto(100) do |i|
#   if i % 5 == 0 && i % 3 == 0
#     puts "FizzBuzz"
#   elsif i % 5 == 0
#     puts "Buzz"
#   elsif i % 3 == 0
#     puts "Fizz"
#   else
#     puts i
#   end

FioFiyo

# Find the maximum 
def maximum(arr)
  arr.inject {|max,num| max = num > max ? num : max}
end

# expect it to return 42 below
result = maximum([2, 42, 22, 02])
puts "max of 2, 42, 22, 02 is: #{result}"

# expect it to return nil when empty array is passed in

FioFiyo

vagrant [vagrant]> pry
[1] pry(main)> "hello"
=> "hello"
[2] pry(main)> puts "h"
h
=> nil
[3] pry(main)> quit
vagrant [vagrant]> ls
git-mania  scavenger_hunt-master  temp_test_file.txt  Vagrantfile
vagrant [vagrant]> touch example.rb

FioFiyo

require 'pry'
require_relative 'methods.rb'
class Animal

attr_accessor :num_legs, :body

	def initialize (num_legs, body = true)
		@num_legs = num_legs
		@body = body
	end

FioFiyo

require 'active_support/all'

@candidates = [
  {
    id: 5,
    years_of_experience: 4,
    github_points: 293,
    languages: ['C', 'Ruby', 'Python', 'Clojure'],
    date_applied: 5.days.ago.to_date,
    age: 26

FioFiyo

# require 'pry'
def benchmark
	start_time = Time.now
	# binding.pry
	yield
	end_time = Time.now
	end_time - start_time

end