Ruby Tips & Tricks

Ruby

• method(:s).source_location + .method(:s).source

  to determine where a method is defined as useful in the STI context Bundle.lastmethod(:weight_in_kg).source_location

  pry(main)> User.new.method(:full_name).source.display
    def full_name
      [first_name, last_name].compact.join(" ")
    end
  => nil
  

• bundle open <gem name>

  bundle open devise (or any other gem) - opens gem source code in the default editor

• object.methods

  Lists all methods of an object. You can do also something like:

  Object.methods - @user.methods

• remember about Struct

  define object on the fly

  class Car < Struct.new(:wheels, :engine)
  end
  
  Car.new 
  => #<struct Car wheels=nil, engine=nil>
  

• use _1 for blocks

  Example, instead of arrs.sum { |e| e.method } ⇒ arrs.sum { _1.method }

• memoization for a multi-line code

  @cached ||= begin
    a = 1
    b = 2
    a + b
  end
  

• Array .dig method

  >> array = [1, 5, [7, 9, 11, ["Treasure"], "Sigma"]]
  => [1, 5, [7, 9, 11, ["Treasure"], "Sigma"]]
  >> array.dig(2, 3, 0)
  => "Treasure"
  

• test your regexps

  go to https://rubular.com/

• endless methods (define method in a single line)

  def double(num) = num * 2
    puts double(5) 
  # 10
  

• .filter_map

  >> [1, 2, 3, 4, 5, 6, 7].filter_map { |x| x.odd? ? x.to_s : nil }
  => ["1", "3", "5", "7"]
  

• Anonymous Class

  Classes can have no name, these class are called anonymous classes. Look at the example below, type it and execute it:

  # anonymous_class.rb
  person = Class.new do
    def say_hi
      'Hi'
    end
  end.new
  
  puts person.say_hi
  puts person.class
  
  # Output
  Hi
  #<Class:0x0000000002696840>
  

• begin/rescue/else/ensure

  https://stackoverflow.com/questions/6279956/ruby-exceptions-why-else

• multiline string with <<~MESSAGE

  def message_body
    <<~MESSAGE
    *New Freight Request:*
    *Merchant:* #{resource.merchant&.name}
    *Mode:* #{resource.transportation_mode.join(', ')}
    *Freight type:* #{resource.freight_type}
    *Origin:* #{resource.origin}
    *Destination:* #{resource.destination}
    *Cargo ready date:* #{resource.cargo_ready_date}
    *Additional note:* #{resource.additional_note}
    *Link to AA:* <#{Rails.application.config_for(:urls).base}/admin/scx_freight_requests/#{resource.id}>
    MESSAGE
  end