Module: Welo

Defined in:

lib/welo.rb,
lib/welo/core/link.rb,
lib/welo/core/matcher.rb,
lib/welo/core/nesting.rb,
lib/welo/base/resource.rb,
lib/welo/core/resource.rb,
lib/welo/core/observation.rb,
lib/welo/core/perspective.rb,
lib/welo/core/relationship.rb

Defined Under Namespace

Modules: CanBeLazy, Resource Classes: DelayedObservation, EpithetMatcher, IdentifyingMatcher, Link, LinksEnumerator, Matcher, Nesting, Observer, Perspective, Relationship

Constant Summary

VERSION =

"0.1.1"

AUTHORS =

['crapooze']

WEBSITE =

"http://github.com/crapooze/welo"

LICENCE =

"MIT"

ObservationStruct =

An ObservationStruct is a special Struct (i.e. a class whose instances are structures).

Class.new(Struct) do
  # The source for an observation instance is the object from which it could
  # be observed. Many applications may not matter, but some do.
  attr_accessor :_source_
  alias :source :_source_

  # Creates a new structure, class which fields correspond to the perspective
  # named name in resource.  If a block is passed, then it is evaluated in
  # the context of the new structure (like Struct.new { ... }).
  #
  # Normally, this method would be inherited by the structure, but we do not want to.
  # Thus we undef it in self.inherited (see self.inherited).
  def self.new_for_resource_in_perspective(resource, name, &blk)
    persp = resource.perspective(name)
    raise ArgumentError.new("no such perspective: #{name} for #{resource}") unless persp
    st = self.new(*persp.fields, &blk)
    st.resource = resource
    st.perspective = name
    st
  end

  # Hook to remove the new_for_resource_in_perspective methods, which is
  # designed only for ObservationStruct but is inherited by the Struct
  # classes if nothing is done.
  def self.inherited(klass)
    klass.instance_eval do 
      undef :new_for_resource_in_perspective
    end
  end

  class << self
    # The resource of an ObservationStruct is the type 
    # of resource it's looking at.
    attr_accessor :resource

    # The perspective of an ObservationStruct is the parts
    # of resource it's looking at.
    attr_accessor :perspective

    # Instanciates a new struct object (i.e., not a Struct class).  The
    # fields are populated from the key/value pairs from hash.  If the
    # structure fields correspond to a relationship, then a
    # DelayedObservation object is created. It will then be the
    # responsibility of the developper to continue observing the delayed
    # observation or not.
    def for_hash(hash)
      vals = members.map do |k|
        rel = resource.relationship(k)
        if rel
          DelayedObservation.new(self, rel, hash[k])
        else
          hash[k]
        end
      end
      self.new(*vals)
    end
  end
end