Trailblazer::Option

Dynamic options to evaluate at runtime.

Trailblazer::Option is the one of the core concept behind traiblazer-operation's step API, reform's populator API etc. It makes us possible to accept any kind of callable objects at compile time and execute them at runtime.

class Song::Create < Trailblazer::Operation
  step Authorize				# Module callable
  step :model					# Method callable
  step ->(ctx, model:, **) { puts model }	# Proc callable
end

This gem is a replacement over declarative-option and has been extracted out from trailblazer-context by identifying common callable patterns.

Option

Trailblazer::Option() accepts :symbol, lambda and any other type of callable as an argument. It will be wrapped accordingly to make an executable, so you can call the value at runtime to evaluate it.

When passing in a :symbol, this will be treated as a method that's called on the given exec_context.

option = Trailblazer::Option(:object_id)
option.(exec_context: Object.new) #=> 2354383

Same with objects responding to .call or #call method.

class CallMe
  def self.call(*args, message:, **options)
    message
  end
end

option = Trailblazer::Option(CallMe)
option.(*args, keyword_arguments: { message: "hello!" }, exec_context: nil) => "hello!"

Notice the usage of keyword_arguments while calling an Option. This is because keyword arguments needs to be forwarded separately in order for them to be compatible with ruby 2.7+.

And of course, passing lambdas. They gets executed within given exec_context when set.

option = Trailblazer::Option( -> { object_id } )
option.(exec_context: Object.new) #=> 1234567

Installation

Add this line to your application's Gemfile:

gem 'trailblazer-option'

Copyright

Copyright (c) 2017-2021 TRAILBLAZER GmbH.

trailblazer-option is released under the MIT License.