class-proxy

A generic (ActiveRecord compatible) class proxy to setup proxy methods for your classes.

The ClassProxy module just needs to be included in a class to get the capabilities provided by this gem.

class UserDb
  include MongoMapper::Document
  include ClassProxy

  primary_fetch  { |args| where(args).first or (raise NotFound) }
  fallback_fetch { |args| Octokit.user(args[:login]) }

  key :name, String
  key :login, String
end

> user = UserDb.fetch(login: 'heelhook')
=> #<UserDb _id: 779813, name: "Pablo Fernandez", login: "heelhook">

In this example the database will be hit with a where(login: 'heelhook') and if it comes back empty Octokit will be used to retrieve the information requested.

The default action (overwritten with after_fallback_fetch, not used in this example) is to return a new object of the parent class (UserDb) with the proper keys set, in this example :id, :name and :login.

class UserDb
  include MongoMapper::Document
  include ClassProxy

  primary_fetch  { |args| where(args).first or (raise NotFound) }
  fallback_fetch { |args| Octokit.user(args[:username]) }
  after_fallback_fetch { |obj| self.username = obj.login }

  key :name, String
  key :reverse_name, String
  key :username, String
  key :public_repos, String
  key :username_uppercase, String

  # Use fallback_fetch since obj is requested
  proxy_methods reverse_name: lambda { |obj| obj.name.reverse }

  # No obj in the lambda, use the UserDb#username method here
  proxy_methods username_uppercase: lambda { username.upcase }
end

With this class now the following can be done:

> user = UserDb.fetch(username: 'heelhook')
=> #<UserDb _id: 779813, name: "Pablo Fernandez", public_repos: "25", username: "heelhook">

Since Octokit.user returned an object which responded to name and our UserDb class has a corresponding attribute, :name was set for us.

> user.name
=> "Pablo Fernandez"

Yet reverse_name is not included, so when we call it, the proxy_method associated with it is used.

> user.reverse_name
=> "zednanreF olbaP"

Since that proxy_method's lambda requested an |obj|, the method fallback_fetch was used and the object returned is used for obj.name.reverse

Let's see what's currently loaded.

> user.no_proxy_username_uppercase
=> nil

Using the proxy. We already have the username in our object, so our username_uppercase proxy method will just use that (no |obj| is used).

> user.username_uppercase
=> "HEELHOOK"

Here the fallback_fetch will not be used since the object has been persisted.

> user.save
=> true
> user = UserDb.fetch(username: 'heelhook')
=> #<UserDb _id: 779813, name: "Pablo Fernandez", public_repos: "25", username: "heelhook">

Like any

ClassProxy is tested against MRI 1.9.3.

Pablo Fernandez: heelhook at littleq . net

Once you've made your great commits:

1. Fork
2. Create a topic branch - git checkout -b my_branch
3. Push to your branch - git push origin my_branch
4. Create a Pull Request from your branch
5. That's it!

Copyright (c) 2012 Pablo Fernandez

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.