Class: Class

Inherits:
Object show all
Defined in:
lib/conject/extended_metaid.rb,
lib/conject/class_ext_object_peers.rb,
lib/conject/class_ext_construct_with.rb,
lib/conject/class_ext_object_context.rb,
lib/conject/class_ext_provide_with_objects.rb

Instance Method Summary collapse

Instance Method Details

#construct_with(*syms) ⇒ Object 



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# File 'lib/conject/class_ext_construct_with.rb', line 4

def construct_with(*syms)
  klass = self

  #
  # Create the .object_definition accessor for this class.
  #
  # The ObjectDefinition stores information # on the dependencies required to
  # build new instances.
  # 
  object_def = Conject::ObjectDefinition.new(:owner => klass, :component_names => syms)
  klass.meta_def :object_definition do
    @object_definition
  end

  # TODO: actually, just use meta_eval here to set the ivar and move on.
  klass.meta_def :set_object_definition do |od| #XXX
    @object_definition = od
  end
  klass.set_object_definition(object_def) # XXX
  klass.meta_eval do private :set_object_definition end # XXX


  #
  # Define internal accessor methods for instances of klass
  #

  # The internal hash of dependencies, keyed by name:
  klass.class_def_private :components do 
    @_components ||= {}
  end
  # Have the components been set for this instance yet?
  klass.class_def_private :components_set? do 
    !@_components.nil?
  end

  # Define an internal reader method per dependency:
  syms.each do |object_name|
    Conject::Utilities.generate_accessor_method_names(object_name).each do |mname|
      class_def_private mname do
        components[object_name]
      end
    end
  end

  # Define the internal setter method that installs dependencies
  # in an instance of klass.
  # #set_components respects the rules set forth in the ObjectDefinition
  # for this class, and will raise a detailed exception if the rules
  # are violated.
  klass.class_def_private :set_components do |component_map|
    return if components_set? # do not repeat.  In inheritance town, a superclass must currently rely on all
                              # of its deps to be declared and set by subclass functionality.

    obj_def = self.class.object_definition
    required = obj_def.component_names
    provided = component_map.keys
    if required.to_set != provided.to_set
      # Explain the diff between what was required and what was actually provided:
      raise Conject::CompositionError.new(
        :object_definition => obj_def,
        :required => required, 
        :provided => provided)
    end

    # set all the components
    components.clear.merge! component_map
  end

  # .object_context_prep is used internally by klass to maintain some state regarding
  # its internal restructuring.
  klass.meta_def :object_context_prep do 
    @object_context_prep ||= {
      :initialize_has_been_wrapped => false
    }
  end
  klass.meta_eval do private :object_context_prep end
  
  klass.meta_def :new do |component_map|
    obj = allocate
    if has_object_definition?
      # Apply the given components
      obj.__send__(:set_components, component_map)
    else
      raise "#{self.class} has an ancestor that uses construct_with, but has not declared any component dependencies.  Will not be able to instantiate!"
    end

    arg_count = obj.method(:initialize).arity
    case arg_count
    when 0
      obj.__send__ :initialize

    when 1, -1  # See Footnote a) at the bottom of this file
      obj.__send__ :initialize, component_map

    else
      # We're not equipped to handle this
      raise "User-defined initialize method defined with #{arg_count} parameters; must either be 0, other wise 1 or -1 (varargs) to receive the component map."
    end

    obj
    
  end
end

#has_object_definition? ⇒ Boolean

Returns:



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# File 'lib/conject/class_ext_construct_with.rb', line 108

def has_object_definition?
  respond_to?(:object_definition) and !object_definition.nil?
end

#object_context ⇒ Object 



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# File 'lib/conject/class_ext_object_context.rb', line 2

def object_context
  Conject.default_object_context
end

#object_peers(*syms) ⇒ Object 



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# File 'lib/conject/class_ext_object_peers.rb', line 3

def object_peers(*syms)
  if !syms.empty?
    @_conject_object_peers = syms
  end
  @_conject_object_peers || []
end

#provide_with_objects(*syms) ⇒ Object 



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# File 'lib/conject/class_ext_provide_with_objects.rb', line 3

def provide_with_objects(*syms)
  klass = self

  # Define an internal reader method per dependency:
  syms.each do |object_name|
    Conject::Utilities.generate_accessor_method_names(object_name).each do |mname|
      class_def_private mname do
        object_context[object_name]
      end
    end
  end
end