c# - Observer pattern with delegate and events using an event array -

we have class manages many queues store data. want user notified when new data added each of these queues. i'd use observer pattern using delegate , events. single event , source, we'd do:

public delegate void newdataaddeddelegate(); public event newdataaddeddelegate newdataadded; 

and observer:

qmanager.newdataadded += new qmanager.newdataaddeddelegate(getnewdatafunc); 

but in case, have, say, 10 queues, each of can receive data arbitrarily. we'd observer functions subscribe individual queue. thought do:

public delegate void newdataaddeddelegate(); public event newdataaddeddelegate [] newdataadded;  // can't 

and in constructor of qmanager:

newdataadded = new newdataaddeddelegate[numberofqueues]; 

and in observer:

qmanager.newdataadded[0] += new qmanager.newdataaddeddelegate(getnewdatafunc0); qmanager.newdataadded[1] += new qmanager.newdataaddeddelegate(getnewdatafunc1); 

but no go, since event expected delegate type, not array of delegates type.

any ideas on how approach problem?

no, events don't work that. options:

• create type exposes event, , have array or collection of type:

  // preferably *don't* expose array... public typewithevent[] queues { { ... } }  // subscription: qmanager.queues[i].newdataadded += ... 

• alternatively, don't use events, , have method:

  private newdataaddededdelegate[] newdataadded;  public void subscribenewdataaddedhandler(int queue,                                           newdataaddeddelegate handler) {     newdataadded[queue] += handler; }  // subscription qmanager.subscribenewdataaddedhandler(0, ...); 

personally sounds me each queue should own object though... make queue manager exposes collection of queues, each of can subscribed individually. (i.e. take first approach.) otherwise queue manager doing work.