class 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 Needle::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 #doing method.
Attributes
The set of options that were given to this interceptor via the with_options method.
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 def initialize @options = { :priority => 0 } @doing = @with = nil end
Public Instance Methods
A convenience method for querying the options on an interceptor definition.
# File lib/needle/interceptor.rb, line 177 def []( name ) @options[ name ] end
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
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
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
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
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
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