Fail fast with wisper events

fail_fast_wisper.rb

require 'wisper'

module FailFastWisper

  def self.included(base)
    base.include Wisper::Publisher
    base.include Helpers
    base.prepend Proxy
  end

  module Proxy
    def call(*)
      catch(:halt) do
        super
      end
    end
  end
  private_constant :Proxy

  module Helpers
    def rescue_halt
      catch(:halt) do
        yield
      end
    end

    def halt!
      throw :halt
    end

    def emit(*args)
      broadcast(*args)
    end

    def emit!(*args)
      broadcast(*args)
      halt!
    end

    def failure!(*args)
      failure(*args)
      halt!
    end

    def failure(*args)
      broadcast(:failure, *args)
    end

    def warning(*args)
      broadcast(:warning, *args)
    end

    def success(*args)
      broadcast(:success, *args)
    end
  end
  private_constant :Helpers

end

test_example.rb

class SomeOperation
  include FailFastWisper

  def call(error_level = 0)
    failure! "Fatal error!" if error_level > 1
    if error_level > 0
      failure "Warning!"
      emit :custom_warning, "Achtung!"
    else
      success "hello!"
    end
  end

end

service = SomeOperation.new
service.on(:success) do |*args|
  puts "SUCCESS! #{args.inspect}"
end
service.on(:custom_warning) do |*args|
  puts "CUSTOM! #{args.inspect}"
end
service.on(:failure) do |*args|
  puts "FAILURE! #{args.inspect}"
end

puts "(0) ================================="
service.call(0)
# SUCCESS! ["hello!"]

puts "(1) ================================="
service.call(1)
# FAILURE! ["Warning!"]
# CUSTOM! ["Achtung!"]

puts "(2) ================================="
service.call(2)
# FAILURE! ["Fatal error!"]

service = SomeOperation.new
  .on(:success)        { |*args| puts "SUCCESS! #{args.inspect}" }
  .on(:custom_warning) { |*args| puts "CUSTOM! #{args.inspect}" }
  .on(:failure)        { |*args| puts "FAILURE! #{args.inspect}" }

puts "(3) ================================="
service.call(0)
# SUCCESS! ["hello!"]

puts "(4) ================================="
service.call(1)
# FAILURE! ["Warning!"]
# CUSTOM! ["Achtung!"]

puts "(5) ================================="
service.call(2)
# FAILURE! ["Fatal error!"]