Module: Flows::Plugin::DependencyInjector

Includes:

InheritanceCallback

Defined in:

lib/flows/plugin/dependency_injector.rb,
lib/flows/plugin/dependency_injector/errors.rb,
lib/flows/plugin/dependency_injector/dependency.rb,
lib/flows/plugin/dependency_injector/dependency_list.rb,
lib/flows/plugin/dependency_injector/dependency_definition.rb

Overview

Allows to inject dependencies on the initialization step.

After including this module you inject dependencies by providing :dependencies key to your initializer:

x = MyClass.new(dependencies: { my_dep: -> { 'Hi' } })
x.my_dep
# => 'Hi'

Keys are dependency names. Dependency will be injected as a public method with dependency name. Values are dependencies itself.

You can also require some dependencies to be present. If required dependency is missed - MissingDependencyError will be raised.

If an optional dependency has no default - MissingDependencyDefaultError will be raised.

For an optional dependency default value must be provided.

You can provide a type for the dependency. Type check uses case equality (===). So, it works like Ruby's case. In case of type mismatch UnexpectedDependencyTypeError will be raised.

dependency :name, type: String # name should be a string

# by the way, you can use lambdas like in Ruby's `case`
dependency :age, type: ->(x) { x.is_a?(Number) && x > 0 && x < 100 }

If you're trying to inject undeclared dependency - UnexpectedDependencyError will be raised.

Inheritance is supported and dependency definitions will be inherited into child classes.

Examples:

class MyClass
  include Flows::Plugin::DependencyInjector

  dependency :logger, required: true
  dependency :name, default: 'Boris', type: String # by default dependency is optional.

  attr_reader :data

  def initializer(data)
    @data = data
  end

  def log_the_name
    logger.call(name)
  end
end

class Logger
  def self.call(msg)
    puts msg
  end
end

x = MyClass.new('DATA', dependencies: {
  logger: Logger
})

x.data
# => 'DATA'

x.name
# => 'Boris'

x.logger.call('Hello')
# prints 'Hello'

x.log_the_name
# prints 'Boris'

Since:

• 0.4.0

Defined Under Namespace

Modules: DSL, InheritanceCallback, InitializePatch Classes: Dependency, DependencyDefinition, DependencyList, Error, MissingDependencyDefaultError, MissingDependencyError, UnexpectedDependencyError, UnexpectedDependencyTypeError

Constant Summary

NO_TYPE =

Placeholder for empty type. We cannot use nil because value can be nil.

Since:

• 0.4.0

:__no_type__

NO_DEFAULT =

Placeholder for empty default. We cannot use nil because value can be nil.

Since:

• 0.4.0

:__no_default__

NO_VALUE =

Placeholder for empty value. We cannot use nil because value can be nil.

Since:

• 0.4.0

:__no_value__

Method Summary

Methods included from InheritanceCallback

#extended, #included