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.

[R] options The set of options that were given to this interceptor via the with_options method.
Classes and Modules
Class Needle::Interceptor::DynamicInterceptor
Public Class methods

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

    # File lib/needle/interceptor.rb, line 81
81:     def initialize
82:       @options = { :priority => 0 }
83:       @doing = @with = nil
84:     end
Public Instance methods
[]( name )

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

     # File lib/needle/interceptor.rb, line 177
177:     def []( name )
178:       @options[ name ]
179:     end
[]=( name, value )

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

     # File lib/needle/interceptor.rb, line 183
183:     def []=( name, value )
184:       @options[ name ] = value
185:     end

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
93:     def action
94:       return @with if @with
95:       raise InterceptorConfigurationError,
96:         "You must specify either 'with' or 'doing'" unless @doing
98:       return proc { |c| @doing ) }
99:     end
doing( &block )

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
149:     def doing( &block )
150:       if @doing
151:         raise InterceptorConfigurationError,
152:           "you cannot redefine 'doing' behavior"
153:       end
155:       if @with
156:         raise InterceptorConfigurationError,
157:           "cannot specify 'doing' after specifying 'with'"
158:       end
160:       if block.nil?
161:         raise InterceptorConfigurationError,
162:           "you must specify a block to 'doing'"
163:       end
165:       @doing = block
166:       self
167:     end
with( &block )

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.


  container.intercept( :foo ).
    with { |c| c.logging_interceptor }
     # File lib/needle/interceptor.rb, line 110
110:     def with( &block )
111:       if @with
112:         raise InterceptorConfigurationError,
113:           "you cannot redefine 'with' behavior"
114:       end
116:       if @doing
117:         raise InterceptorConfigurationError,
118:           "cannot specify 'with' after specifying 'doing'"
119:       end
121:       if block.nil?
122:         raise InterceptorConfigurationError,
123:           "you must specify a block to 'with'"
124:       end
126:       @with = block
127:       self
128:     end
with!( &block )

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


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

Merge the given opts hash into the interceptors options hash.

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