Class: Dry::System::Container

Inherits:
Object
  • Object
show all
Extended by:
Configurable, Container::Mixin, Plugins
Defined in:
lib/dry/system/container.rb,
lib/dry/system/stubs.rb

Overview

Abstract container class to inherit from

Container class is treated as a global registry with all system components. Container can also import dependencies from other containers, which is useful in complex systems that are split into sub-systems.

Container can be finalized, which triggers loading of all the defined components within a system, after finalization it becomes frozen. This typically happens in cases like booting a web application.

Before finalization, Container can lazy-load components on demand. A component can be a simple class defined in a single file, or a complex component which has init/start/stop lifecycle, and it's defined in a boot file. Components which specify their dependencies using Import module can be safely required in complete isolation, and Container will resolve and load these dependencies automatically.

Furthermore, Container supports auto-registering components based on dir/file naming conventions. This reduces a lot of boilerplate code as all you have to do is to put your classes under configured directories and their instances will be automatically registered within a container.

Every container needs to be configured with following settings:

  • `:name` - a unique container identifier

  • `:root` - a system root directory (defaults to `pwd`)

  • `:system_dir` - directory name relative to root, where bootable components

    can be defined in `boot` dir this defaults to `system`
    

Examples:

class MyApp < Dry::System::Container
  configure do |config|
    config.name = :my_app

    # this will auto-register classes from 'lib/components'. ie if you add
    # `lib/components/repo.rb` which defines `Repo` class, then it's
    # instance will be automatically available as `MyApp['repo']`
    config.auto_register = %w(lib/components)
  end

  # this will configure $LOAD_PATH to include your `lib` dir
  load_paths!('lib')
end

Defined Under Namespace

Modules: Stubs

Class Method Summary collapse

Methods included from Plugins

enabled_plugins, inherited, loaded_dependencies, register, registry, use

Class Method Details

.after(event, &block) ⇒ Object

This method is part of a private API. You should avoid using this method if possible, as it may be removed or be changed in the future.


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# File 'lib/dry/system/container.rb', line 607

def after(event, &block)
  hooks[event] << block
end

.auto_register!(dir) { ... } ⇒ self

Auto-registers components from the provided directory

Typically you want to configure auto_register directories, and it will work automatically. Use this method in cases where you want to have an explicit way where some components are auto-registered, or if you want to exclude some components from being auto-registered

Examples:

class MyApp < Dry::System::Container
  configure do |config|
    # ...
  end

  # with a dir
  auto_register!('lib/core')

  # with a dir and a custom registration block
  auto_register!('lib/core') do |config|
    config.instance do |component|
      # custom way of initializing a component
    end

    config.exclude do |component|
      # return true to exclude component from auto-registration
    end
  end
end

Parameters:

  • dir (String)

    The dir name relative to the root dir

Yields:

  • AutoRegistrar::Configuration

Returns:

  • (self)

See Also:


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# File 'lib/dry/system/container.rb', line 432

def auto_register!(dir, &block)
  auto_registrar.(dir, &block)
  self
end

.auto_registrarObject

This method is part of a private API. You should avoid using this method if possible, as it may be removed or be changed in the future.


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# File 'lib/dry/system/container.rb', line 527

def auto_registrar
  @auto_registrar ||= config.auto_registrar.new(self)
end

.boot(name, opts = {}, &block) ⇒ self

Registers finalization function for a bootable component

By convention, boot files for components should be placed in `%system_dir/boot` and they will be loaded on demand when components are loaded in isolation, or during finalization process.

Examples:

# system/container.rb
class MyApp < Dry::System::Container
  configure do |config|
    config.root = Pathname("/path/to/app")
    config.name = :core
    config.auto_register = %w(lib/apis lib/core)
  end

# system/boot/db.rb
#
# Simple component registration
MyApp.boot(:db) do |container|
  require 'db'

  container.register(:db, DB.new)
end

# system/boot/db.rb
#
# Component registration with lifecycle triggers
MyApp.boot(:db) do |container|
  init do
    require 'db'
    DB.configure(ENV['DB_URL'])
    container.register(:db, DB.new)
  end

  start do
    db.establish_connection
  end

  stop do
    db.close_connection
  end
end

# system/boot/db.rb
#
# Component registration which uses another bootable component
MyApp.boot(:db) do |container|
  use :logger

  start do
    require 'db'
    DB.configure(ENV['DB_URL'], logger: logger)
    container.register(:db, DB.new)
  end
end

# system/boot/db.rb
#
# Component registration under a namespace. This will register the
# db object under `persistence.db` key
MyApp.namespace(:persistence) do |persistence|
  require 'db'
  DB.configure(ENV['DB_URL'], logger: logger)
  persistence.register(:db, DB.new)
end

Parameters:

  • name (Symbol)

    a unique identifier for a bootable component

Returns:

  • (self)

See Also:


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# File 'lib/dry/system/container.rb', line 219

def boot(name, opts = {}, &block)
  if components.key?(name)
    raise DuplicatedComponentKeyError, "Bootable component #{name.inspect} was already registered"
  end

  component =
    if opts[:from]
      boot_external(name, opts, &block)
    else
      boot_local(name, opts, &block)
    end
  self

  components[name] = component
end

.boot_external(identifier, from:, key: nil, namespace: nil, &block) ⇒ Object

This method is part of a private API. You should avoid using this method if possible, as it may be removed or be changed in the future.


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# File 'lib/dry/system/container.rb', line 237

def boot_external(identifier, from:, key: nil, namespace: nil, &block)
  component = System.providers[from].component(
    identifier, key: key, namespace: namespace, finalize: block, container: self
  )

  booter.register_component(component)

  component
end

.boot_local(identifier, namespace: nil, &block) ⇒ Object

This method is part of a private API. You should avoid using this method if possible, as it may be removed or be changed in the future.


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# File 'lib/dry/system/container.rb', line 248

def boot_local(identifier, namespace: nil, &block)
  component = Components::Bootable.new(identifier, container: self, namespace: namespace, &block)

  booter.register_component(component)

  component
end

.boot_pathObject

This method is part of a private API. You should avoid using this method if possible, as it may be removed or be changed in the future.


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# File 'lib/dry/system/container.rb', line 522

def boot_path
  root.join("#{config.system_dir}/boot")
end

.booterObject

This method is part of a private API. You should avoid using this method if possible, as it may be removed or be changed in the future.


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# File 'lib/dry/system/container.rb', line 517

def booter
  @booter ||= config.booter.new(boot_path)
end

.component(identifier, **options) ⇒ Object

This method is part of a private API. You should avoid using this method if possible, as it may be removed or be changed in the future.


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# File 'lib/dry/system/container.rb', line 542

def component(identifier, **options)
  if (component = booter.components.detect { |c| c.identifier == identifier })
    component
  else
    Component.new(
      identifier,
      loader: config.loader,
      namespace: config.default_namespace,
      separator: config.namespace_separator,
      inflector: config.inflector,
      **options,
    )
  end
end

.configure(&block) ⇒ self

Configures the container

Examples:

class MyApp < Dry::System::Container
  configure do |config|
    config.root = Pathname("/path/to/app")
    config.name = :my_app
    config.auto_register = %w(lib/apis lib/core)
  end
end

Returns:

  • (self)

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# File 'lib/dry/system/container.rb', line 104

def configure(&block)
  super(&block)
  load_paths!(config.system_dir)
  hooks[:configure].each { |hook| instance_eval(&hook) }
  self
end

.enable_stubs!Object

Enables stubbing container's components

Examples:

require 'dry/system/stubs'

MyContainer.enable_stubs!
MyContainer.finalize!

MyContainer.stub('some.component', some_stub_object)

Returns:

  • Container


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# File 'lib/dry/system/stubs.rb', line 26

def self.enable_stubs!
  super
  extend ::Dry::System::Container::Stubs
  self
end

.finalize!(freeze: true) {|_self| ... } ⇒ self

Finalizes the container

This triggers importing components from other containers, booting registered components and auto-registering components. It should be called only in places where you want to finalize your system as a whole, ie when booting a web application

Examples:

# system/container.rb
class MyApp < Dry::System::Container
  configure do |config|
    config.root = Pathname("/path/to/app")
    config.name = :my_app
    config.auto_register = %w(lib/apis lib/core)
  end
end

# You can put finalization file anywhere you want, ie system/boot.rb
MyApp.finalize!

# If you need last-moment adjustments just before the finalization
# you can pass a block and do it there
MyApp.finalize! do |container|
  # stuff that only needs to happen for finalization
end

Yields:

  • (_self)

Yield Parameters:

Returns:

  • (self)

    frozen container


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# File 'lib/dry/system/container.rb', line 294

def finalize!(freeze: true, &block)
  return self if finalized?

  yield(self) if block

  importer.finalize!
  booter.finalize!
  manual_registrar.finalize!
  auto_registrar.finalize!

  @__finalized__ = true

  self.freeze if freeze
  self
end

.finalized?TrueClass, FalseClass

Return if a container was finalized

Returns:

  • (TrueClass, FalseClass)

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# File 'lib/dry/system/container.rb', line 261

def finalized?
  @__finalized__.equal?(true)
end

.hooksObject

This method is part of a private API. You should avoid using this method if possible, as it may be removed or be changed in the future.


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# File 'lib/dry/system/container.rb', line 612

def hooks
  @__hooks__ ||= Hash.new { |h, k| h[k] = [] }
end

.import(other) ⇒ Object

Registers another container for import

Examples:

# system/container.rb
class Core < Dry::System::Container
  configure do |config|
    config.root = Pathname("/path/to/app")
    config.auto_register = %w(lib/apis lib/core)
  end
end

# apps/my_app/system/container.rb
require 'system/container'

class MyApp < Dry::System::Container
  configure do |config|
    config.root = Pathname("/path/to/app")
    config.auto_register = %w(lib/apis lib/core)
  end

  import core: Core
end

Parameters:

  • other (Hash, Dry::Container::Namespace)

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# File 'lib/dry/system/container.rb', line 137

def import(other)
  case other
  when Hash then importer.register(other)
  when Dry::Container::Namespace then super
  else
    raise ArgumentError, "+other+ must be a hash of names and systems, or a Dry::Container namespace"
  end
end

.importerObject

This method is part of a private API. You should avoid using this method if possible, as it may be removed or be changed in the future.


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# File 'lib/dry/system/container.rb', line 537

def importer
  @importer ||= config.importer.new(self)
end

.inherited(klass) ⇒ Object

This method is part of a private API. You should avoid using this method if possible, as it may be removed or be changed in the future.


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# File 'lib/dry/system/container.rb', line 617

def inherited(klass)
  new_hooks = Container.hooks.dup

  hooks.each do |event, blocks|
    new_hooks[event].concat(blocks)
    new_hooks[event].concat(klass.hooks[event])
  end

  klass.instance_variable_set(:@__hooks__, new_hooks)
  super
end

.init(name) ⇒ self

Boots a specific component but calls only `init` lifecycle trigger

This way of booting is useful in places where a heavy dependency is needed but its started environment is not required

Examples:

MyApp.init(:persistence)

Parameters:

  • name (Symbol)

    The name of a registered bootable component

Returns:

  • (self)

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# File 'lib/dry/system/container.rb', line 340

def init(name)
  booter.init(name)
  self
end

.injector(options = {}) ⇒ Object

Builds injector for this container

An injector is a useful mixin which injects dependencies into automatically defined constructor.

Examples:

# Define an injection mixin
#
# system/import.rb
Import = MyApp.injector

# Use it in your auto-registered classes
#
# lib/user_repo.rb
require 'import'

class UserRepo
  include Import['persistence.db']
end

MyApp['user_repo].db # instance under 'persistence.db' key

Parameters:

  • options (Hash) (defaults to: {})

    injector options


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# File 'lib/dry/system/container.rb', line 462

def injector(options = {})
  Dry::AutoInject(self, options)
end

.load_component(key) ⇒ Object

This method is part of a private API. You should avoid using this method if possible, as it may be removed or be changed in the future.


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# File 'lib/dry/system/container.rb', line 582

def load_component(key)
  return self if key?(key)

  component(key).tap do |component|
    if component.boot?
      booter.start(component)
    else
      root_key = component.root_key

      if (bootable_dep = component(root_key)).boot?
        booter.start(bootable_dep)
      elsif importer.key?(root_key)
        load_imported_component(component.namespaced(root_key))
      end

      if !key?(key)
        load_local_component(component)
      end
    end
  end

  self
end

.load_pathsObject

This method is part of a private API. You should avoid using this method if possible, as it may be removed or be changed in the future.


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# File 'lib/dry/system/container.rb', line 512

def load_paths
  @load_paths ||= []
end

.load_paths!(*dirs) ⇒ self

Sets load paths relative to the container's root dir

Examples:

class MyApp < Dry::System::Container
  configure do |config|
    # ...
  end

  load_paths!('lib')
end

Parameters:

  • dirs (Array<String>)

Returns:

  • (self)

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# File 'lib/dry/system/container.rb', line 381

def load_paths!(*dirs)
  dirs.map(&root.method(:join)).each do |path|
    next if load_paths.include?(path)
    load_paths << path
    $LOAD_PATH.unshift(path.to_s)
  end
  self
end

.load_registrations!(name) ⇒ Object


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# File 'lib/dry/system/container.rb', line 391

def load_registrations!(name)
  manual_registrar.(name)
  self
end

.manual_registrarObject

This method is part of a private API. You should avoid using this method if possible, as it may be removed or be changed in the future.


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# File 'lib/dry/system/container.rb', line 532

def manual_registrar
  @manual_registrar ||= config.manual_registrar.new(self)
end

.require_component(component) ⇒ Object

This method is part of a private API. You should avoid using this method if possible, as it may be removed or be changed in the future.


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# File 'lib/dry/system/container.rb', line 558

def require_component(component)
  return if key?(component.identifier)

  unless component.file_exists?(load_paths)
    raise FileNotFoundError, component
  end

  require_path(component.path)

  yield
end

.require_from_root(*paths) ⇒ Object

Requires one or more files relative to the container's root

Examples:

# single file
MyApp.require_from_root('lib/core')

# glob
MyApp.require_from_root('lib/**/*')

Parameters:

  • paths (Array<String>)

    one or more paths, supports globs too


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# File 'lib/dry/system/container.rb', line 478

def require_from_root(*paths)
  paths.flat_map { |path|
    path.to_s.include?('*') ? Dir[root.join(path)] : root.join(path)
  }.each { |path|
    require path.to_s
  }
end

.require_path(path) ⇒ Object

This method is part of a private API. You should avoid using this method if possible, as it may be removed or be changed in the future.

Allows subclasses to use a different strategy for required files.

E.g. apps that use `ActiveSupport::Dependencies::Loadable#require_dependency` will override this method to allow container managed dependencies to be reloaded for non-finalized containers.


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# File 'lib/dry/system/container.rb', line 577

def require_path(path)
  require path
end

.resolve(key) ⇒ Object


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# File 'lib/dry/system/container.rb', line 505

def resolve(key)
  load_component(key) unless finalized?

  super
end

.rootPathname

Returns container's root path

Examples:

class MyApp < Dry::System::Container
  configure do |config|
    config.root = Pathname('/my/app')
  end
end

MyApp.root # returns '/my/app' pathname

Returns:

  • (Pathname)

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# File 'lib/dry/system/container.rb', line 500

def root
  config.root
end

.shutdown!Object


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# File 'lib/dry/system/container.rb', line 360

def shutdown!
  booter.shutdown
  self
end

.start(name) ⇒ self

Boots a specific component

As a result, `init` and `start` lifecycle triggers are called

Examples:

MyApp.start(:persistence)

Parameters:

  • name (Symbol)

    the name of a registered bootable component

Returns:

  • (self)

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# File 'lib/dry/system/container.rb', line 322

def start(name)
  booter.start(name)
  self
end

.stop(name) ⇒ self

Stop a specific component but calls only `stop` lifecycle trigger

Examples:

MyApp.stop(:persistence)

Parameters:

  • name (Symbol)

    The name of a registered bootable component

Returns:

  • (self)

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# File 'lib/dry/system/container.rb', line 355

def stop(name)
  booter.stop(name)
  self
end