C # Event Event aggregator

The event aggregator is used to centrally manage events ' subscriptions (Subscribe) and processing (Handle), and to use event aggregators, it is first understood that the event is essentially a class.

Traditional + = and-= deficiencies:

1, management is very troublesome, 2, inconvenient to expand.

So try to use event aggregator to solve this problem.

First, use a unified interface to implement the unified markup for the event:

public interface ievent{  }

event, you need to have a corresponding event handler (EventHandler), which is unified using a unified interface Ieventhandler, Ieventhandler contains only one method for handling events Handle

public interface Ieventhandler<in tevent> where tevent:class, ievent{    void Handler (Tevent @event);}

Event aggregator Interface Ieventaggregator needs to contain at least two methods: Subscription (Subscribe) and release (Publish)

public interface ieventaggregator{    void subscribe<tevent> (ieventhandler<tevent> handler) where Tevent:class, IEvent;    void publish<tevent> (Tevent @event) where Tevent:class, IEvent;}

The next step is to implement this interface: Eventaggregator

Example:

usingSystem;usingSystem.Collections.Generic;usingSystem.Linq;usingSystem.Text;namespaceeventaggregatortest{ Public InterfaceIEvent {} Public Interfaceieventhandler<inchTevent>whereTevent:class, IEvent {voidHandler (tevent @event); }     Public InterfaceIeventaggregator {voidSubscribe<tevent> (ieventhandler<tevent> handler)whereTevent:class, IEvent; voidPublish<tevent> (tevent @event)whereTevent:class, IEvent; }     Public classEventaggregator:ieventaggregator {//all the event and the corresponding handler are registered in this dictionary .        Private ReadOnlyDictionary<type, list<Object>> _eventhandlers =NewDictionary<type, list<Object>>();  Public voidSubscribe<tevent> (ieventhandler<tevent> handler)whereTevent:class, IEvent {varEventType =typeof(tevent); if(_eventhandlers.containskey (EventType)) {varHandlers =_eventhandlers[eventtype]; if(Handlers! =NULL) {handlers.                ADD (handler); }                Else{handlers=Newlist<Object>{handler}; }            }            Else{_eventhandlers.add (EventType,Newlist<Object>{handler}); }        }         Public voidPublish<tevent> (tevent @event)whereTevent:class, IEvent {varEventType =@event.            GetType (); if(_eventhandlers.containskey (EventType)&& _eventhandlers[eventtype]! =NULL&& _eventhandlers[eventtype]. Count >0)            {                varHandlers =_eventhandlers[eventtype]; foreach(varHandlerinchhandlers) {                    varEventHandler = Handler asIeventhandler<tevent>; EventHandler?.                Handler (@event); }            }        }    }     Public classmealdoneevent:ievent { Public stringDishname {Get;Private Set; }  PublicMealdoneevent (stringdishname) {Dishname=Dishname; }    }     Public classMealdoneeventhandler:ieventhandler<mealdoneevent>    {        Private ReadOnly string_name;  PublicMealdoneeventhandler (stringname) {_name=name; }        #regionImplementation of Ieventhandler<in Mealdoneevent> Public voidHandler (Mealdoneevent @event) {Console.WriteLine ($"{_name} is {@event}. Dishname}"); }        #endregion    }}

Call:

usingeventaggregatortest;usingSystem;usingSystem.Collections.Generic;usingSystem.Linq;usingSystem.Text;namespaceeventaggregatordemo{classProgram {Static voidMain (string[] args) {            varEventaggregator =NewEventaggregator (); Eventaggregator.subscribe (NewMealdoneeventhandler ("Zhang San")); Eventaggregator.subscribe (NewMealdoneeventhandler ("John Doe")); Eventaggregator.subscribe (NewMealdoneeventhandler ("Harry")); Eventaggregator.publish (NewMealdoneevent ("have a big meal"));        Console.readkey (); }    }}

C # Event Event aggregator