Example of how to use the u-observers `#on()` and `#once()` methods to handle events and their custom scopes.

with_u-observers.rb

require 'bundler/inline'
require 'securerandom'

gemfile do
  source 'https://rubygems.org'
  gem 'u-observers', '~> 2.2.1'
end

class DoSomethingWithFiles
  include Micro::Observers

  RemoveFile = -> file { File.delete(file) }
  PrintFilename = -> file { puts File.basename(file) }

  def initialize(content1:, content2:)
    @content1, @content2 = content1, content2
  end

  def call
    write_content_in_a_file(@content1)
    write_content_in_a_file(@content2)

    observers.notify!(:print_filename, :remove_file)
  end

  private

    def write_content_in_a_file(content)
      File.open("./#{SecureRandom.hex}.txt", 'w') { |f| f.puts(content); f }.tap do |file|
        observers.once(event: :remove_file, call: RemoveFile, with: file)
        observers.once(event: :print_filename, call: PrintFilename, with: file)
      end
    end
end

DoSomethingWithFiles.new(content1: 'foo', content2: 'bar').call

without_u-observers.rb

require 'securerandom'

class DoSomethingWithFiles
  def initialize(content1:, content2:)
    @content1, @content2 = content1, content2
  end

  def call
    file1 = write_content_in_a_file(@content1)
    file2 = write_content_in_a_file(@content2)

    [file1, file2].each { |file| puts File.basename(file) }
    [file1, file2].each { |file| File.delete(file.path) }
  end

  private

    def write_content_in_a_file(content)
      File.open("./#{SecureRandom.hex}.txt", 'w') { |f| f.puts(content); f }
    end
end

DoSomethingWithFiles.new(content1: 'foo', content2: 'bar').call