Class: Needle::ServicePoint

Inherits:
Object
  • Object
show all
Defined in:
lib/needle/service-point.rb

Overview

A “service point” is a definition of a service. Just as a class defines the behavior of an object, so does a service point describes a service. In particular, a service point also knows how to instantiate a service.

A ServicePoint should never be directly instantiated. Instead, define services via the interfaces provided by Container.

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(container, name, opts = {}, &callback) ⇒ ServicePoint

Create a new service point that references the given container and has the given name. The associated callback will be used to instantiate the service on demand.

The :model option is used to tell Needle which style of life-cycle management should be used for the service. It defaults to :singleton. The model must be a symbol that refers to a service model that has been registered in the root :service_models service.

The :pipeline option is mutually exclusive with :model. It must be an array of symbols (or strings) that define the instantiation pipeline to use for this service. Each element must correspond to an entry in the :pipeline_elements service.


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# File 'lib/needle/service-point.rb', line 54

def initialize( container, name, opts={}, &callback )
  @name = name
  @container = container
  @callback = callback
  @pipeline = Needle::Pipeline::Collection.new self
  @chain = nil
  @mutex = QueryableMutex.new

  if opts[:pipeline]
    elements = opts[:pipeline]
  else
    model = opts[:model] || :singleton
    elements = @container[:service_models][model]
  end

  elements.each { |element| @pipeline.add element, opts }
end

Instance Attribute Details

#containerObject (readonly)

A reference to the container that contains this service point.


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# File 'lib/needle/service-point.rb', line 35

def container
  @container
end

#nameObject (readonly)

The name of this service point, as it is known to the container that it was registered in.


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# File 'lib/needle/service-point.rb', line 32

def name
  @name
end

#pipelineObject (readonly)

The reference to the instantiation pipeline used by this service point.


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# File 'lib/needle/service-point.rb', line 38

def pipeline
  @pipeline
end

Instance Method Details

#fullnameObject

Returns the fully-qualified name of the service point, with the point's name, its container's name, and all of its container's ancestors' names concatenated together with dot characters, i.e. “one.two.three”.


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# File 'lib/needle/service-point.rb', line 75

def fullname
  container_name = @container.fullname
  if container_name
    "#{container_name}.#{@name}"
  else
    @name.to_s
  end
end

#instanceObject

Return the service instance represented by this service point. Depending on the style of lifecycle management chosen for this service point, this may or may not be a new instance for every invocation of this method.


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# File 'lib/needle/service-point.rb', line 99

def instance
  unless @chain
    @mutex.synchronize do
      @chain = @pipeline.chain_to( @callback ) unless @chain
    end
  end

  @chain.call( @container, self )
end

#interceptor(interceptor) ⇒ Object

Adds the given interceptor definition to this service point. The parameter should act like an instance of Interceptor.


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# File 'lib/needle/service-point.rb', line 86

def interceptor( interceptor )
  element = @pipeline.get( :interceptor )
  unless element
    @chain = nil
    @pipeline.add( :interceptor )
    element = @pipeline.get( :interceptor )
  end
  element.interceptors << interceptor
end