olc.rb

Puppet::Type.type(:foo).provide(:olc) do
  mk_resource_methods

  def self.instances
    ['a', 'b', 'c'].map do |i|
      new ({
        :ensure => :present,
        :name   => "bar#{i}",
      })
    end
  end

  def self.prefetch(resources)
    # prefetch from instances
    existing = instances
    resources.keys.each do |name|
      if provider = existing.find { |r| r.name == name }
        # this is used to generate @property_hash so we know if there is a need to create resources
        resources[name].provider = provider
      end
    end

    # Instantiate @modified, no resources are planned to be modified
    @modified = false
    # Get the names of all resources, existing or in the catalog
    @all_names = (existing.map { |r| r.name } + resources.keys).uniq
  end

  def self.post_resource_eval
    # If any resource needed to be created
    if @modified
      # Here you can call slaptest() to create all the resources using @all_names
      p @all_names
    end
  end

  # This class method updates @modified
  def self.modified!
    @modified = true
  end

  def exists?
    # A resource exists if it was found in instances
    @property_hash[:ensure] == :present
  end

  def create
    # We don't do anything here, we just indicate that resources need to be modified
    self.class.modified!
  end

  def destroy
    # How do we destroy?
  end
end