Observer pattern C# using generics
I am trying to implement the observer pattern with a slight twist, the Subject and Observer are the same class. For example,
class myclass
{
public delegate void UpdateHandler(object sender);
public event UpdateHandler UpdateEvent;
public Attach(myclass obj){ // use delegate to attach update function of obj}
public Update(object sender){ // do something with sender}
public Notify() { // use UpdateEvent to update all attached obj's }
}
This should work fine. Now I want to remove the performance penalty imposed by boxing and unboxing everytime i have an update event, thus I remove the "object" based implementation and am trying to use generics. For example,
class myclass<Tin, Tout>
{
public delegate void UpdateHandler(Tout sender);
public event UpdateHandler UpdateEvent;
public Attach(myclass<Tin,Tout> obj)
{ // use delegate to attach update function of obj}
public Update(Tin sender){ // do something with sender}
public Notify()
{ // use UpdateEvent to update all attached obj's
// but 开发者_运维问答now we have to send Tout
}
}
This does not work, because I have one EventHandler, it can either be Tin or Tout, but not both. How do I get around this ? Any other suggestions to change design also welcome. Thanks very much for reading this and I hope this is clear enough to understand the question.
Change your event handler too:
public delegate void UpdateHandler<Tin>(Tin sender);
public event UpdateHandler<Tin> UpdateEvent;
Check out this question and responses. It is a very good implementation of pub/sub with strongly-typed generics.
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