README.md
# Adaptor
[](https://travis-ci.org/aldesantis/adaptor)
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[](https://codeclimate.com/github/aldesantis/adaptor/maintainability)
Adaptor makes it easy to implement the [Adapter pattern](https://en.wikipedia.org/wiki/Adapter_pattern) in Ruby.
## Installation
Add this line to your application's Gemfile:
```ruby
gem 'adaptor'
```
And then execute:
$ bundle
Or install it yourself as:
$ gem install adaptor
## Usage
### Single adaptor mode
You can use the library in single-adaptor mode:
```ruby
module DocumentProcessor
class Pdf
include Adaptor
def self.supports?(document)
document.mime_type == 'application/pdf'
end
def initialize(document)
@document = document
end
def build_thumbnail
# something with @document
end
end
class Word
include Adaptor
def self.supports?(document)
document.mime_type == 'application/msword'
end
def initialize(document)
@document = document
end
def build_thumbnail
# something with @document
end
end
end
module DocumentProcessor
include Adaptor::Loader
register Pdf, Word
end
# You can use #load_adaptor! if you want to raise an
# Adaptor::NoAdaptorError when no adaptor is found.
thumbnail = DocumentProcessor.load_adaptor(document).build_thumbnail
```
### Multiple adaptor mode
If it suits your use case, you can use multiple-adaptor mode:
```ruby
module NotificationProcessor
class Email
include Adaptor
def self.supports?(notification)
notification.user.email.present?
end
def initialize(notification)
@notification = notification
end
def deliver
# ...
end
end
class Sms
include Adaptor
def self.supports?(notification)
notification.user.phone.present?
end
def initialize(notification)
@notification = notification
end
def deliver
# ...
end
end
end
module MultipleAdaptorLoader
include Adaptor::Loader
register Email, Sms
end
# You can use #load_adaptors! if you want to raise an
# Adaptor::NoAdaptorError when no adaptors are found.
NotificationProcessor.load_adaptors(notification).each(&:deliver)
```
### Multiple arguments
Note that there is no limit to the number of arguments you can pass to the adaptors' `.supports?`
and `.new` methods. Here's an example that checks support only with one argument, but initializes
with multiple:
```ruby
module DocumentProcessor
class Pdf
include Adaptor
def self.supports?(document)
document.mime_type == 'application/pdf'
end
def initialize(document, options)
@document = document
@options = options
end
def build_thumbnail
# something with @document and @options
end
end
class Word
include Adaptor
def self.supports?(document)
document.mime_type == 'application/msword'
end
def initialize(document, options)
@document = document
@options = options
end
def build_thumbnail
# something with @document and @options
end
end
end
module DocumentProcessor
include Adaptor::Loader
register Pdf, Word
end
# You can use #load_adaptor! if you want to raise an
# Adaptor::NoAdaptorError when no adaptor is found.
thumbnail = DocumentProcessor.load_adaptor(document, stamp: true).build_thumbnail
```
As you can see, whatever you pass to `.load_adaptor` or `.load_adaptors` will be forwarded to
`.supports?` and `.new`, according to the methods' respective arity.
## Contributing
Bug reports and pull requests are welcome on GitHub at https://github.com/aldesantis/adaptor. This
project is intended to be a safe, welcoming space for collaboration, and contributors are expected
to adhere to the [Contributor Covenant](http://contributor-covenant.org) code of conduct.
## License
The gem is available as open source under the terms of the [MIT License](https://opensource.org/licenses/MIT).
## Code of Conduct
Everyone interacting in the Adaptor project’s codebases, issue trackers, chat rooms and mailing
lists is expected to follow the [code of conduct](https://github.com/[USERNAME]/adaptor/blob/master/CODE_OF_CONDUCT.md).