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Adapter

A simple interface to anything.

Defining an Adapter

An adapter requires 4 methods to work: read, write, delete and clear.

Adapter.define(:memory) do
  def read(key)
    decode(client[key_for(key)])
  end

  def write(key, value)
    client[key_for(key)] = encode(value)
  end

  def delete(key)
    client.delete(key_for(key))
  end

  def clear
    client.clear
  end
end

Note: in order for things to be most flexible, always wrap key with key_for(key) which will ensure that pretty much anything can be a key. Also, by default encode and decode are included and they Marshal.dump and Marshal.load. Feel free to override these if you prefer JSON serialization or something else.

Once you have defined an adapter, you can get a class of that adapter like this:

Adapter[:memory]

This returns a dynamic class with your adapting methods included and an initialize method that takes a client. This means you can get an instance of the adapter by using new and passing the client (in this instance a boring hash):

adapter = Adapter[:memory].new({}) # sets {} to client
adapter.write('foo', 'bar')
adapter.read('foo') # 'bar'
adapter.delete('foo')
adapter.fetch('foo', 'bar') # returns bar and sets foo to bar

get and [] are aliased to read. set and []= are aliased to write.

Note: You can also optionally provide a lock method. See the memcached and redis adapters for more on locking.

Extending Adapters

Adapters can be defined using a block, a module, or a module and a block. This allows very flexibly overriding specific things in an adapter to create a new adapter, without having to redo all of the work. See examples/overriding_serialization.rb for an example of this.

Note on Patches/Pull Requests

  • Fork the project.

  • Make your feature addition or bug fix.

  • Add tests for it. This is important so we don't break it in a future version unintentionally.

  • Commit, do not mess with rakefile, version, or history. (if you want to have your own version, that is fine, but bump version in a commit by itself so we can ignore when we pull)

  • Send us a pull request. Bonus points for topic branches.

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