Getting started with Ruby (on Rails)

Ruby language basics

• Ruby in 20 minutes
•  the Ruby REPL is irb
• expressions in a string are escaped with "#{expression}"
• print function is puts
• functions are defined like:

  def myfun(somearg = "default")
    # do something with somearg
  end

• arguments can have default value
• functions can be called like:

  myfun
  myfun()
  myfun "some other arg"
  myfun("some other arg")

• classes are defined like:

  class MyClass
    attr_accessor :somearg
    def initialize(somearg = "default")
      @somearg = somearg
    end
    # do something with @somearg anywhere in the class
  end

• class instantiation is done with the "new" keyword:

  myclass = MyClass.new("some other arg")

• the instance variable @somearg is private
• the methods defined in the class are public by default
• the attribute accessor :somearg allows to get and set the instance variable (public). Usage: myclass.somearg and myclass.somearg= "something new"
• information about a class can be retrieved with MyClass.instance_methods(show_inherited = true)
• See more on Ruby-Doc
• iterations
• for each loop
  

  @names.each do |name|
    puts "Hello #{name}!"
  end

• conditionals
• if-else block
  

  def say_bye
    if @names.nil?
      puts "..."
    elsif @names.respond_to?("join")
      # Join the list elements with commas
      puts "Goodbye #{@names.join(", ")}.  Come back soon!"
    else
      puts "Goodbye #{@names}.  Come back soon!"
    end
  end

Some additional info:

• @/@@ vs. self
• method visibility
• variables vs constants
• ! (aka. bang) in method names means danger
• ? is indicating a boolean return type

Ruby on Rails basics

• Getting started with Ruby on Rails explains the project structure
• ActiveRecord Basics explains that
• anything that subclasses ApplicationRecord is mapped to a database table
• validations are a thing of ApplicationRecord. See more here. 
• ActiveRecord Migrations explains how database migrations are done

rspec testing framework basics

...coming up...
in the meantime here are some resources:

• https://dev.to/hanachin/how-to-minimize-rspec-describecontext-nesting-4179
• http://www.betterspecs.org/
• https://stackoverflow.com/questions/5359558/when-to-use-rspec-let

My IDE choice

• VSCode with extensions:
• Ruby
• Ruby Solargraph
• ruby-rubocop
• lourenci.go-to-spec