c# - Notify change in calculated property -

there have been similar questions on site have not found answer works, post again.

public myclass {     public person person1 {get; set;}     public person person2 {get; set;}    calculatedproperty     {            { return person1.salary + (person2.salary/2) ; }    }  }  public class person {   public double salary     { get; set;} } 

i want able notify changes in calculatedproperty whenever person1.salary and/or person2.salary changes.

i have tried adding onpropertychanged("calculatedproperty") on setters of person1 , person2 not work (and understand why), can't find way notify changes. please =)

(is there way use objectdataprovider this?... been trying too...)

you need person implement inotifypropertychanged too, register 2 properties have. once propertychanged invoked salary on either of them, invoke propertychanged on calculatedproperty

void personpropertychanged(object sender, propertychangedeventargs e) {     if(e.propertyname == "salary")         onpropertychanged("calculatedproperty"); } 

just remember unregister when person changed.

update:

as jim said, setter should this:

private person _person; public person person {     { return _person; }     set     {         if (equals(value, _person)) return;          if (_person != null)             _person.propertychanged -= personpropertychanged;          _person = value;          if(_person != null)             _person.propertychanged += personpropertychanged;          onpropertychanged("person");     } }