Do you find yourself writing a lot of boilerplate code like that?
def initialize(network_provider, api_token)
@network_provider = network_provider
@api_token = api_token
end
def self.call(network_provider, api_token)
new(network_provider, api_token).call
end
Gem provides a simple DSL for getting rid of it. It offers an alternative to using Struct.new
which does not check for number of parameters provided in initializer, exposes getters and instantiates unecessary class instances.
Smart Init offers a unified API convention for stateless service objects, accepting values in initializer and exposing one public class method call
which instantiates new objects and accepts arguments passed to initializer.
Check out this blog post for my reasoning behind this approach to service object pattern.
In your Gemfile
gem 'smart_init'
You can use it either by extending a module:
class ApiClient
extend SmartInit
initialize_with :network_provider, :api_token
end
or subclassing:
class ApiClient < SmartInit::Base
initialize_with :network_provider, :api_token
end
Now you can just:
object = ApiClient.new(network_provider: Faraday.new, api_token: 'secret_token')
# <ApiClient:0x007fa16684ec20 @network_provider=Faraday<...>, @api_token="secret_token">
If you omit a required attribute an ArgumentError
will be thrown:
object = ApiClient.new(network_provider: Faraday.new)
# ArgumentError (missing required attribute api_token)
You can also use is_callable
method:
class Calculator < SmartInit::Base
initialize_with :data
is_callable
def call
...
result
end
end
Calculator.call(data: data) => result
Optionally you can customize a callable method name:
class Routine < SmartInit::Base
initialize_with :params
is_callable method_name: :run!
def run!
...
end
end
Routine.run!(params: params)
You can use hash based, default argument values:
class Adder < SmartInit::Base
initialize_with :num_a, num_b: 2
is_callable
def call
num_a + num_b
end
end
Adder.call(num_a: 2) => 4
Adder.call(num_a: 2, num_b: 3) => 5
Alternatively you can use a legacy API without hash arguments and default values:
class Calculator < SmartInit::Base
initialize_with_args :data
is_callable
def call
...
result
end
end
Calculator.call(data) => result