# This module hides the implementation details that
# relationships are stored in a hash, which is bound to change anyway.
# Also, it allows to *fail fast* when trying to access a relationship
# that is not defined in a model (via the relationship! method)

module RelationshipAccess

  def relationship(name, repository_name = default_repository_name)
    relationships(repository_name)[name]
  end

  def relationship!(name, repository_name = default_repository_name)
    unless relationship = relationship(name, repository_name)
      raise(ArgumentError, "No relationship #{name.inspect} for #{self.name} in #{repository_name}")
    end
    relationship
  end

end