C#•2y ago

❔ Listening for object properties changed

let's say i have a object:

class Foo
{
  public int Counter {get;set;}
}

class Foo
{
  public int Counter {get;set;}
}

i would like to attach an event listener automatically for its all properties so if i do foo.Counter++; some method will invoked without manually adding code to every property

10 Replies

TheRanger•2y ago

class Foo
{
  private int _counter;
  public int Counter
  {
      get => _counter;
      set {
        _counter = value;
        OnCounterChanged();
      }
  }
   
   private void OnCounterChanged()
   {
      // fire your event listener
   }
}

class Foo
{
  private int _counter;
  public int Counter
  {
      get => _counter;
      set {
        _counter = value;
        OnCounterChanged();
      }
  }
   
   private void OnCounterChanged()
   {
      // fire your event listener
   }
}

your only way afaik

CrosRoad95OP•2y ago

i want to avoid this

TheRanger•2y ago

i dont think that's possible

CrosRoad95OP•2y ago

DoSomething(new Foo(), name => {
   Console.WriteLine("Property: " + name + " has changed")
})

DoSomething(new Foo(), name => {
   Console.WriteLine("Property: " + name + " has changed")
})

i need it to get delta change between previous and current state of object these data i want to send across network so i want to avoid sending data that has not changed the idea is to get know which properties changed and send only these which changed

TheRanger•2y ago

well you can probably do it with some system reflection shenanigans

CrosRoad95OP•2y ago

perhaps i could store old value as hashcode and then compare them has a different idea, make a method to change state, ChangeState(x => x.Counter, 2)

TheRanger•2y ago

yeah that could work

CrosRoad95OP•2y ago

ChangeState(x => x.Counter, 2);
ChangeState(x => x.Counter, 3);
ChangeState(x => x.Counter, 4);

ChangeState(x => x.Counter, 2);
ChangeState(x => x.Counter, 3);
ChangeState(x => x.Counter, 4);

"changeState" will know Counter change, it will immediately schedule a task to update client state but if another state change in next 10ms then cancel previous synchronization, that way 3 changes of same property will yield a single update

333fred•2y ago

Is this a viewmodel for some ui? Because it sounds like what you want is INotifyPropertyChanged and CommunityToolkit.Mvvm, which has source generators to generate the boilerplate for you

Accord•2y ago

Was this issue resolved? If so, run /close - otherwise I will mark this as stale and this post will be archived until there is new activity.

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❔ Listening for object properties changed