launchkit-codes

class Array
  def my_map
    ary = []
    
    self.each do |elem|
      ary << yield(elem)
    end
    
    ary
  end

launchkit-codes

def yield_with_return_value
  hello_world = yield

  puts hello_world
end

yield_with_return_value { "Hello World!" } # => Hello World!

launchkit-codes

def yield_with_arguments
  hello = 'Hello'
  world = 'World!'

  yield(hello, world)
end

yield_with_arguments { |hello, world| puts "#{hello} #{world}" } # => Hello World!

launchkit-codes

def optional_block
  yield if block_given?
end

optional_block # => nil
optional_block { puts 'optional block' } # => optional block

launchkit-codes

def yield_without_block
  yield
end

yield_without_block # => LocalJumpError (no block given (yield))

launchkit-codes

def one_yield
  yield
end

def multiple_yields
  yield
  yield
end

one_yield { puts "one yield" }

launchkit-codes

computer.cores = 2

launchkit-codes

computer[:screens] = 2

launchkit-codes

require 'ostruct'

computer = OpenStruct.new(ram: '4GB')

launchkit-codes

computer.instance_variables # => [:@table, :@modifiable]