Ruby Blocks examples

ruby_blocks.rb

## Execute Around

def time_it(label)
  start_time = Time.now
  yield
  elapsed_time = Time.now - start_time
  puts "#{label} took #{elapsed_time} seconds"
end

time_it("Sleepy code") do
  #run some code
  sleep(0.5)
end

# Checking something and using yield

def with_checking(description)
  puts "Checking #{description}"
  result = yield
  result ? "Ok" : "Failed"
end

with_checking("temperature") { 3 < 5 }
with_checking("another_example") { 3 < 5 }


# Block initializer

module Jem
  class Specification
    attr_accessor :name, :description, :version
    
    def initialize
      @version = '1.0.0'
      yield(self) if block_given?
    end
  end
end


spec = Jem::Specification.new do |s|
  s.description = "Description"
  s.version = "2.0.0"
  s.name = "My Jem"
end

## Manage Resources

class File
  def self.my_open(filename, mode)
    file = self.new(filename, mode)
    
    return file unless block_given?
    
    begin
      yield(file)
    ensure
      file.close
    end
  end
end


File.my_open("letter.txt", "w") do |f|
  f.puts "Hello"
  f.puts "Goodbye"
end