chassis_repo

ChassisRepo

ChassisRepo is the repo part of the Chassis project which will be used for MagLev.

Support Libraries

Chassis is implemented with help from a few smaller libraries. A unified interface if you do not want to know about such things.

• Errors with TNT
• Object initialization with Lift
• Interchangeable objects with Interchange

Installation

Add this line to your application's Gemfile:

gem 'chassis_repo'

And then execute:

$ bundle

Or install it yourself as:

$ gem install chassis_repo

Data Access

Chassis includes a repository using the query pattern as well. The repository pattern is perfect because it does not require knowledge about your persistence layer. It is the access layer. A null, in-memory, and Redis adapter are included. You can subclass these adapters to make your own. Chassis::Repo::Delegation can be included in other classes to delegate to the repository.

Here's an example:

class CustomerRepo
  extend Chassis::Repo::Delegation
end

Now there are CRUD methods available on CustomerRepo that delegate to the repository for Customer objects. Chassis::Persistence can be included in any object. It will make the object compatible with the matching repo.

class Customer
  include Chassis::Persistence
end

Now Customer responds to id, save, and repo. repo looks for a repository class matching the class name (e.g. CustomerRepo). Override as you see if.

More on my blog here.

Chassis::DirtySession

A proxy object used to track assignments. Wrap an object in a dirty session to see what changed and what it changed to.

Person = Struct.new :name

adam = Person.new 'adam'

session = Chassis::DirtySession.new adam
session.clean? # => true
session.dirty? # => false

session.name = 'Adman'

session.dirty? # => true
session.clean? # => false

session.named_changed? # => true
session.changed # => set of values changed
session.new_values # => { name: 'Adman' }
session.original_values # => { name: 'adam' }

session.reset! # reset everything back to normal

Chassis::Logger

Chassis includes the logger-better gem to refine the standard library logger. Chassis::Logger default the logdev argument to Chassis.stream. This gives a unified place to assign all output. The log level can also be controlled by the LOG_LEVEL environment variable. This makes it possible to restart/boot the application with a new log level without redeploying code.

Chassis::Observable

A very simple implementation of the observer pattern. It is different from the standard library implementation for two reasons:

• you don't need to call changed for notify_observers to work.
• notify_obsevers includes self as first argument to all observers
• there is only the add_observer method.

Contributing

1. Fork it
2. Create your feature branch (git checkout -b my-new-feature)
3. Commit your changes (git commit -am 'Add some feature')
4. Push to the branch (git push origin my-new-feature)
5. Create new Pull Request