Question

I’m a bit unsure on how I’d word this question, so pardon me if this is duplicate.

Basically I want to call UpdateModifiedTimestamp everytime a property is changed. This is just a sample class I wrote up pretty quickly, but should explain what I’m trying to achieve.

Everytime Firstname, Lastname, or Phone is changed it should update the ModifiedOn property.

public class Student {
   public DateTime ModifiedOn { get; private set; }
   public readonly DateTime CreatedOn;
   public string Firstname { set; get; }
   public string Lastname { set; get; }
   public string Phone { set; get; }

   public Student() {
      this.CreatedOn = DateTime.Now();
   }

   private void UpdateModifiedTimestamp() {
      this.ModifiedOn = DateTime.Now();
   }
}

Answer 1

What you are describing sounds pretty close to the property change notification usually done via the INotifyPropertyChanged interface. Implementing this interface would give you a little more generic solution to your problem:

public class Student :INotifyPropertyChanged
{
   public string Firstname { set; get; }
   public event PropertyChangedEventHandler PropertyChanged;

   private void NotifyPropertyChanged(String info)
   {
      UpdateModifiedTimestamp(); // update the timestamp
      if (PropertyChanged != null)
      {
          PropertyChanged(this, new PropertyChangedEventArgs(info));
      }
   }

   string _firstname;
   public string Firstname  //same for other properties
   {
     get
     {
         return _firstname;
     }

     set
     {
        if (value != _firstname)
        {
            _firstname = value;
            NotifyPropertyChanged("Firstname");
        }
     }
   }
 }

This approach would make the change notification available to consumers of your class as well, if that’s what you are shooting for, a different solution probably would be preferable.