ModuleBuilder
ModuleBuilder gives you the ability to create modules that are customizable for different situations. Are you creating a module that has an adapter, but don't want to expose a setter on the including class because it's not a public API? ModuleBuilder can help with that! Do you have two implementations of some behavior that have different tradeoffs? Do you want to offer both through one easy-to-use syntax? ModuleBuilder can do that too!
Come see what ModuleBuilder will help you with today!
Installation
Add this line to your application's Gemfile:
gem "module_builder"
And then execute:
$ bundle
Or install it yourself as:
$ gem install module_builder
Usage
ModuleBuilder revolves around the concept of Builders that are responsible for
building modules based on your specification. For convenience, there is a
Buildable
module that you can mix in to give your module building
superpowers.
You configure Builders through two channels: class-level configuration and instance-level state. There are three types of class-level configuration: stateless inclusions, stateless extensions, and defined hooks.
Stateless methods do not give much more power than just using a standard set of
include
s and extend
s. However, they help you organize your code in an
easily extensible fashion.
You can use instance-level state within defined hooks to customize the behavior of the built module. If you need to conditionally define a method based on the configuration, you want to look here.
Stateless Inclusions
The builder simply include
s stateless inclusions into the built module. There
are no customization hooks here, just a single place to specify all the modules
you want to include
in your built module.
class StatelessInclusionBuilder < ModuleBuilder::Builder
def inclusions
[Comparable, Enumerable]
end
end
StatelessInclusionBuilder.new.module.ancestors
#=> [#<Module>, Enumerable, Comparable]
Stateless Extensions
The builder adds all stateless extensions into the Module#extended
hook of
the built module so they are extended onto anything that extends the built
module.
module Quack
def quack
"quack"
end
end
class QuackingBuilder < ModuleBuilder::Builder
def extensions
[Quack]
end
end
class Duck
extend QuackingBuilder.new.module
end
Duck.quack #=> "quack"
Defined Hooks
Defined hooks are where you can do the heavy customization when building a module. They are arbitrary methods that the builder invokes during its initialization. Add any behavior that you want to make customizable via the state that you give to the builder as a defined hook.
module Walk
def walk
"step, step, step"
end
end
class WalkingBuilder < ModuleBuilder::Builder
def hooks
[:rename_walk]
end
def inclusions
[Walk]
end
private
def rename_walk
return unless @walk_method
@module.__send__(:alias_method, @walk_method, :walk)
@module.__send__(:undef_method, :walk)
end
end
class Duck
include WalkingBuilder.new(:walk_method => :waddle).module
end
Duck.new.waddle #=> "step, step, step"
Duck.new.walk #=> NoMethodError
Buildable Module
Explicitly instantiating a Builder and accessing the module that it built is
clunky. To gain easy access to a consistent syntax for your module, you can
include the Buildable
module and specify the builder you want to use when
building your module.
class MyBuilder < ModuleBuilder::Builder
end
module BuildableExample
include ModuleBuilder::Buildable
builder MyBuilder
end
module IncludingModule
include BuildableExample.new(:state => "value")
end
Buildable
defaults to using a Builder
defined within the current module.
You can rely on that instead of using the DSL for specifying the builder.
module OtherBuildableExample
include ModuleBuilder::Buildable
class Builder < ModuleBuilder::Builder
end
end
module OtherIncludingModule
include OtherBuildableExample.new(:my_config_value => "awesome")
end
When a Buildable
module is included without the use of its constructor, the
default version of the module is included in the descendant class or module.
module BuildableExample
include ModuleBuilder::Buildable
class Builder < ModuleBuilder::Builder
end
end
module IncludingModule
include BuildableExample
end
Development
After checking out the repo, run bin/setup
to install dependencies. Then, run
rake spec
to run the tests. You can also run bin/console
for an interactive
prompt that will allow you to experiment.
When writing code, you can use the helper application Guard to
automatically run tests and coverage tools whenever you modify and save a file.
This helps to eliminate the tedium of running tests manually and reduces the
change that you will accidentally forget to run the tests. To use Guard, run
bundle exec guard
.
Before committing code, run rake
to check that the code conforms to the style
guidelines of the project, that all of the tests are green (if you're writing a
feature; if you're only submitting a failing test, then it does not have to
pass!), and that the changes are sufficiently documented.
To install this gem onto your local machine, run bundle exec rake install
. To
release a new version, update the version number in version.rb
, and then run
bundle exec rake release
, which will create a git tag for the version, push
git commits and tags, and push the .gem
file to rubygems.org.
Contributing
Bug reports and pull requests are welcome on GitHub at https://github.com/michaelherold/module_builder. This project is intended to be a safe, welcoming space for collaboration, and contributors are expected to adhere to the Contributor Covenant code of conduct.
Supported Ruby Versions
This library aims to support and is tested against the following Ruby versions:
- Ruby 1.9.3
- Ruby 2.0
- Ruby 2.1
- Ruby 2.2
- JRuby 1.7 (in Ruby 1.9 mode)
- JRuby 9.0
If something doesn't work on one of these versions, it's a bug.
This library may inadvertently work (or seem to work) on other Ruby versions, however support will only be provided for the versions listed above.
If you would like this library to support another Ruby version or implementation, you may volunteer to be a maintainer. Being a maintainer entails making sure all tests run and pass on that implementation. When something breaks on your implementation, you will be responsible for providing patches in a timely fashion. If critical issues for a particular implementation exist at the time of a major release, support for that Ruby version may be dropped.
Versioning
This library aims to adhere to Semantic Versioning 2.0.0. Violations of this scheme should be reported as bugs. Specifically, if a minor or patch version is released that breaks backward compatibility, that version should be immediately yanked and/or a new version should be immediately released that restores compatibility. Breaking changes to the public API will only be introduced with new major versions. As a result of this policy, you can (and should) specify a dependency on this gem using the Pessimistic Version Constraint with two digits of precision. For example:
spec.add_dependency "module_builder", "~> 0.1"
Credits
The original implementation of this library was based on the Builder within the virtus gem by Piotr Solnica, which I used for inspiration. Pieces of it live on, but the current product expands on the original.
The idea for the library came from a conversation about the
best way to configure a module once it is included in a class. Grégory
Horion's comment lead me down the path of using Module.new
as the
base for this library.
License
The gem is available as open source under the terms of the MIT License.