Merge pull request #4 from dry-rb/container-and-mixin

Split extraction to mixin and contaner versions with reference to #3

Author: nepalez

README.md

@@ -42,7 +42,7 @@ $ gem install dry-initializer
 require 'dry-initializer'
 
 class User
-  extend Dry::Initializer
+  extend Dry::Initializer::Mixin
 
   # Params of the initializer along with corresponding readers
   param  :name, type: String
@@ -76,13 +76,51 @@ class User
 end
 ```
 
+### Container Version
+
+Instead of extending a class with the `Dry::Initializer::Mixin`, you can include a container with the initializer:
+
+```ruby
+require 'dry-initializer'
+
+class User
+  # notice `{}` syntax for the block, not `do..end`
+  include Dry::Initializer.define {
+    param  :name,  type: String
+    param  :role,  default: proc { 'customer' }
+    option :admin, default: proc { false }
+  }
+end
+```
+
+Now you do not pollute a class with new variables, but isolate them in a special "container" module with the initializer and attribute readers. This method should be preferred when you don't need subclassing.
+
+If you still need the DSL (`param` and `option`) to be inherited, use the direct extension:
+
+```ruby
+require 'dry-initializer'
+
+class BaseService
+  extend Dry::Initializer::Mixin
+  alias_method :dependency, :param
+end
+
+class ShowUser < BaseService
+  dependency :user
+
+  def call
+    puts user&.name
+  end
+end
+```
+
 ### Params and Options
 
 Use `param` to define plain argument:
 
 ```ruby
 class User
-  extend Dry::Initializer
+  extend Dry::Initializer::Mixin
 
   param :name
   param :email
@@ -97,7 +135,7 @@ Use `option` to define named (hash) argument:
 
 ```ruby
 class User
-  extend Dry::Initializer
+  extend Dry::Initializer::Mixin
 
   option :name
   option :email
@@ -112,7 +150,7 @@ All names should be unique:
 
 ```ruby
 class User
-  extend Dry::Initializer
+  extend Dry::Initializer::Mixin
 
   param  :name
   option :name # => raises #<SyntaxError ...>
@@ -125,7 +163,7 @@ By default both params and options are mandatory. Use `:default` key to make the
 
 ```ruby
 class User
-  extend Dry::Initializer
+  extend Dry::Initializer::Mixin
 
   param  :name,  default: proc { 'Unknown user' }
   option :email, default: proc { 'unknown@example.com' }
@@ -144,7 +182,7 @@ Set `nil` as a default value explicitly:
 
 ```ruby
 class User
-  extend Dry::Initializer
+  extend Dry::Initializer::Mixin
 
   param  :name
   option :email, default: proc { nil }
@@ -163,7 +201,7 @@ If you need to **assign** proc as a default value, wrap it to another one:
 
 ```ruby
 class User
-  extend Dry::Initializer
+  extend Dry::Initializer::Mixin
 
   param :name_proc, default: proc { proc { 'Unknown user' } }
 end
@@ -176,7 +214,7 @@ Proc will be executed in a scope of new instance. You can refer to other argumen
 
 ```ruby
 class User
-  extend Dry::Initializer
+  extend Dry::Initializer::Mixin
 
   param :name
   param :email, default: proc { "#{name.downcase}@example.com" }
@@ -190,7 +228,7 @@ user.email # => 'andrew@example.com'
 
 ```ruby
 class User
-  extend Dry::Initializer
+  extend Dry::Initializer::Mixin
 
   param :name, default: -> (obj) { 'Dude' }
 end
@@ -204,7 +242,7 @@ You cannot define required parameter after optional ones. The following example
 
 ```ruby
 class User
-  extend Dry::Initializer
+  extend Dry::Initializer::Mixin
 
   param :name, default: proc { 'Unknown name' }
   param :email # => #<SyntaxError ...>
@@ -217,7 +255,7 @@ To set type constraint use `:type` key:
 
 ```ruby
 class User
-  extend Dry::Initializer
+  extend Dry::Initializer::Mixin
 
   param :name, type: String
 end
@@ -233,7 +271,7 @@ You can use plain Ruby classes and modules as type constraint (see above), or us
 
 ```ruby
 class User
-  extend Dry::Initializer
+  extend Dry::Initializer::Mixin
 
   param :name, type: Dry::Types::Coercion::String
 end
@@ -243,7 +281,7 @@ Or you can define custom constraint as a proc:
 
 ```ruby
 class User
-  extend Dry::Initializer
+  extend Dry::Initializer::Mixin
 
   param :name, type: proc { |v| raise TypeError if String === v }
 end
@@ -262,7 +300,7 @@ To skip the reader, use `reader: false`:
 
 ```ruby
 class User
-  extend Dry::Initializer
+  extend Dry::Initializer::Mixin
 
   param :name
   param :email, reader: false
@@ -283,7 +321,7 @@ Subclassing preserves all definitions being made inside a superclass:
 
 ```ruby
 class User
-  extend Dry::Initializer
+  extend Dry::Initializer::Mixin
 
   param :name
 end

benchmarks/options.rb

@@ -2,28 +2,28 @@
 
 require "dry-initializer"
 class NoOptsTest
-  extend Dry::Initializer
+  extend Dry::Initializer::Mixin
 
   param  :foo
   option :bar
 end
 
 class DefaultsTest
-  extend Dry::Initializer
+  extend Dry::Initializer::Mixin
 
   param  :foo, default: proc { "FOO" }
   option :bar, default: proc { "BAR" }
 end
 
 class TypesTest
-  extend Dry::Initializer
+  extend Dry::Initializer::Mixin
 
   param  :foo, type: String
   option :bar, type: String
 end
 
 class DefaultsAndTypesTest
-  extend Dry::Initializer
+  extend Dry::Initializer::Mixin
 
   param  :foo, type: String, default: proc { "FOO" }
   option :bar, type: String, default: proc { "BAR" }

benchmarks/params.rb

@@ -13,7 +13,7 @@ def initialize(foo, bar)
 
 require "dry-initializer"
 class DryTest
-  extend Dry::Initializer
+  extend Dry::Initializer::Mixin
 
   param :foo
   param :bar

benchmarks/params_vs_options.rb

@@ -3,15 +3,15 @@
 require "dry-initializer"
 
 class ParamDefaults
-  extend Dry::Initializer
+  extend Dry::Initializer::Mixin
 
   param :foo, default: proc { "FOO" }
   param :bar, default: proc { "BAR" }
   param :baz, default: proc { "BAZ" }
 end
 
 class OptionDefaults
-  extend Dry::Initializer
+  extend Dry::Initializer::Mixin
 
   option :foo, default: proc { "FOO" }
   option :bar, default: proc { "BAR" }

benchmarks/several_defaults.rb

@@ -2,31 +2,31 @@
 
 require "dry-initializer"
 class WithoutDefaults
-  extend Dry::Initializer
+  extend Dry::Initializer::Mixin
 
   param :foo
   param :bar
   param :baz
 end
 
 class WithOneDefault
-  extend Dry::Initializer
+  extend Dry::Initializer::Mixin
 
   param :foo
   param :bar
   param :baz, default: proc { "BAZ" }
 end
 
 class WithTwoDefaults
-  extend Dry::Initializer
+  extend Dry::Initializer::Mixin
 
   param :foo
   param :bar, default: proc { "BAR" }
   param :baz, default: proc { "BAZ" }
 end
 
 class WithThreeDefaults
-  extend Dry::Initializer
+  extend Dry::Initializer::Mixin
 
   param :foo, default: proc { "FOO" }
   param :bar, default: proc { "BAR" }

benchmarks/with_defaults.rb

@@ -11,7 +11,7 @@ def initialize(foo: "FOO", bar: "BAR")
 
 require "dry-initializer"
 class DryTest
-  extend Dry::Initializer
+  extend Dry::Initializer::Mixin
 
   option :foo, default: proc { "FOO" }
   option :bar, default: proc { "BAR" }

benchmarks/with_types.rb

@@ -13,7 +13,7 @@ def initialize(foo:, bar:)
 
 require "dry-initializer"
 class DryTest
-  extend Dry::Initializer
+  extend Dry::Initializer::Mixin
 
   option :foo, type: String
   option :bar, type: String

benchmarks/with_types_and_defaults.rb

@@ -13,7 +13,7 @@ def initialize(foo: "FOO", bar: "BAR")
 
 require "dry-initializer"
 class DryTest
-  extend Dry::Initializer
+  extend Dry::Initializer::Mixin
 
   option :foo, type: String, default: proc { "FOO" }
   option :bar, type: String, default: proc { "BAR" }

benchmarks/without_options.rb

@@ -11,7 +11,7 @@ def initialize(foo:, bar:)
 
 require "dry-initializer"
 class DryTest
-  extend Dry::Initializer
+  extend Dry::Initializer::Mixin
 
   option :foo
   option :bar

dry-initializer.gemspec

@@ -13,7 +13,7 @@ Gem::Specification.new do |gem|
 
   gem.required_ruby_version = ">= 2.2"
 
-  gem.add_development_dependency "guard-rspec", "~> 4.0"
-  gem.add_development_dependency "rake", "~> 10.5"
+  gem.add_development_dependency "rspec", "~> 3.0"
+  gem.add_development_dependency "rake", "~> 10.0"
   gem.add_development_dependency "dry-types", "~> 0.5.1"
 end

lib/dry/initializer.rb

@@ -9,45 +9,13 @@ module Initializer
     require_relative "initializer/argument"
     require_relative "initializer/arguments"
     require_relative "initializer/builder"
+    require_relative "initializer/mixin"
 
-    # Declares a plain argument
-    #
-    # @param [#to_sym] name
-    #
-    # @option options [Object]  :default The default value
-    # @option options [#call]   :type    The type constraings via `dry-types`
-    # @option options [Boolean] :reader (true) Whether to define attr_reader
-    #
-    # @return [self] itself
-    #
-    def param(name, **options)
-      arguments_builder.define_initializer(name, option: false, **options)
-      self
-    end
-
-    # Declares a named argument
-    #
-    # @param  (see #param)
-    # @option (see #param)
-    # @return (see #param)
-    #
-    def option(name, **options)
-      arguments_builder.define_initializer(name, option: true, **options)
-      self
-    end
-
-    private
-
-    def arguments_builder
-      @arguments_builder ||= begin
-        builder = Builder.new
-        include builder.mixin
-        builder
+    def self.define(&block)
+      Module.new do |container|
+        container.extend Dry::Initializer::Mixin
+        container.instance_eval(&block)
       end
     end
-
-    def inherited(klass)
-      klass.instance_variable_set(:@arguments_builder, arguments_builder)
-    end
   end
 end