DetectorGraph::FuturePublisher< T > Class Template Reference

Publish data to the graph for future evaluation. More...

Collaboration diagram for DetectorGraph::FuturePublisher< T >:

Public Member Functions
	FuturePublisher ()
void	SetGraph (Graph *aGraph)
void	PublishOnFutureEvaluation (const T &aData)
	Publish a new version of T to the Graph for future evaluation. More...

Protected Attributes
Graph *	mGraph

Detailed Description

template<class T>
class DetectorGraph::FuturePublisher< T >

Publish data to the graph for future evaluation.

Detectors inherit from a FuturePublisher<T> to implement the behavior of being a Publisher of T for a future/next evaluation. This differs from a normal Publisher in a very fundamental way, it enables a detector to publish something to an upstream topic - thus constructing a feedback loop. Normally, publishing to an upstream topic would create a directed cycle in the graph thus making it impossible to be topologically sorted.

Using FuturePublisher a detector can implement a feedback loop while still making sure the topological nature of graph evaluation is preserved.

A class FooDetector acquires the "FuturePublisher of BarTopicState" behavior by inheriting FuturePublisher templated to BarTopicState.

This is a template class and so it must be kept minimal to prevent code bloat. This class serves a tiny purpose:

• Document in a clear way the "FuturePublishing" behavior of an inheriting Detector.
• Caches a pointer to the Graph
• Abstracts the act of Publishing to the Graph into a type-safe method.

The only requirement to use the FuturePublisher functionality is to call Detector::SetupFuturePublishing from the inheriting Detector's constructor:

Below is an example:

class ResetDetector : public DetectorGraph::Detector
, public DetectorGraph::SubscriberInterface<EventCount>
, public DetectorGraph::FuturePublisher<Reset>
{
public:
    ResetDetector(DetectorGraph::Graph* graph) : DetectorGraph::Detector(graph)
    {
        Subscribe<EventCount>(this);
        SetupFuturePublishing<Reset>(this);
    }

    void Evaluate(const EventCount& aEventCount)
    {
        if (aEventCount.count >= kMaxCount)
        {
            PublishOnFutureEvaluation(Reset());
        }
    }

    static const int kMaxCount = 5;
};

When implementing feedback loops in a graph one should also consider DetectorGraph::Lag as in some cases it's more general and extensible.

Definition at line 61 of file futurepublisher.hpp.

Constructor & Destructor Documentation

FuturePublisher()

template<class T>

DetectorGraph::FuturePublisher< T >::FuturePublisher ( )

inline

Definition at line 65 of file futurepublisher.hpp.

Member Function Documentation

PublishOnFutureEvaluation()

template<class T>

void DetectorGraph::FuturePublisher< T >::PublishOnFutureEvaluation ( const T &  aData )

inline

Publish a new version of T to the Graph for future evaluation.

Definition at line 77 of file futurepublisher.hpp.

SetGraph()

template<class T>

void DetectorGraph::FuturePublisher< T >::SetGraph ( Graph *  aGraph )

inline

Definition at line 69 of file futurepublisher.hpp.

Member Data Documentation

mGraph

template<class T>

Graph* DetectorGraph::FuturePublisher< T >::mGraph

protected

Definition at line 84 of file futurepublisher.hpp.

---

The documentation for this class was generated from the following file:

• include/futurepublisher.hpp