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Needle::Interceptor

This represents the definition of an interceptor as it is attached to a service point. Instances of Interceptor are also used for configuring themselves programmatically.

You will almost never instantiate an Interceptor object directly. Instead, use the Container#intercept method. You can then configure the new interceptor by chaining methods of the new object together, quite readably:

container.intercept( :foo ).with! { some_interceptor }.
  with_options( :arg => :value )

You can also create new interceptors on the fly via the Interceptor#doing method.

Attributes

options[R]

The set of options that were given to this interceptor via the with_options method.

Public Class Methods

new() click to toggle source

Create a new Interceptor definition. By default, it has no implementation and a priority of 0.

# File lib/needle/interceptor.rb, line 81
def initialize
  @options = { :priority => 0 }
  @doing = @with = nil
end

Public Instance Methods

[]( name ) click to toggle source

A convenience method for querying the options on an interceptor definition.

# File lib/needle/interceptor.rb, line 177
def []( name )
  @options[ name ]
end
[]=( name, value ) click to toggle source

A convenience method for setting the options on an interceptor definition.

# File lib/needle/interceptor.rb, line 183
def []=( name, value )
  @options[ name ] = value
end
action() click to toggle source

Returns the action that was specified for this interceptor as a proc instance. This will either be the block passed to with, or a proc that wraps the instantiation of a DynamicInterceptor (when doing was used).

If neither with nor doing were specified, an InterceptorConfigurationError is raised.

# File lib/needle/interceptor.rb, line 93
def action
  return @with if @with
  raise InterceptorConfigurationError,
    "You must specify either 'with' or 'doing'" unless @doing

  return proc { |c| DynamicInterceptor.new( @doing ) }
end
doing( &block ) click to toggle source

This allows new interceptors to be defined “on-the-fly”. The associated block must accept two parameters–an object representing the chain of interceptors, and the context of the current method invocation. The block should then invoke process_next on the chain (passing the context as the lone parameter) when the next element of the chain should be invoked.

You should only call doing once per interceptor, and never after invoking with on the same interceptor.

# File lib/needle/interceptor.rb, line 149
def doing( &block )
  if @doing
    raise InterceptorConfigurationError,
      "you cannot redefine 'doing' behavior"
  end

  if @with
    raise InterceptorConfigurationError,
      "cannot specify 'doing' after specifying 'with'"
  end

  if block.nil?
    raise InterceptorConfigurationError,
      "you must specify a block to 'doing'"
  end

  @doing = block
  self
end
with( &block ) click to toggle source

Sets the action for this interceptor to be that defined by the interceptor returned when the block is executed. You can only invoke with once, and never after previously invoking doing on the same interceptor instance.

Usage:

container.intercept( :foo ).
  with { |c| c.logging_interceptor }
# File lib/needle/interceptor.rb, line 110
def with( &block )
  if @with
    raise InterceptorConfigurationError,
      "you cannot redefine 'with' behavior"
  end

  if @doing
    raise InterceptorConfigurationError,
      "cannot specify 'with' after specifying 'doing'"
  end

  if block.nil?
    raise InterceptorConfigurationError,
      "you must specify a block to 'with'"
  end

  @with = block
  self
end
with!( &block ) click to toggle source

This is identical to with, but it wraps the block in another proc that calls instance_eval on the container, with the block.

Usage:

container.intercept( :foo ).
  with! { logging_interceptor }
# File lib/needle/interceptor.rb, line 137
def with!( &block )
  with { |c| c.instance_eval( &block ) }
end
with_options( opts={} ) click to toggle source

Merge the given opts hash into the interceptors options hash.

# File lib/needle/interceptor.rb, line 170
def with_options( opts={} )
  @options.update opts
  self
end

[Validate]

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