Using an attribute to throw an exception in .NET

Question

Hello, Is it possible to use some kind of attribute to throw an exception. This is what I mean. Instead of doing this:

public int Age
{
    get
    {
     return this.age;
    }

    set
    {
     this.age = value;
     NotifyPropertyChanged("Age");

     if (value < 18)
     {
      throw new Exception("age < 18");
     }

    }
}

Do something like this:

[Range(18,100, ErrorMessage="Must be older than 18")]
public int Age
{
    get
    {
     return this.age;
    }

    set
    {
     this.age = value;
     NotifyPropertyChanged("Age");
    }
}

Any help would be greatly appreciated!

Best Regards, Kiril

Answer 1

You're looking for an AOP (Aspect Oriented Programming) library, which can do this quite easily. I would recommend giving PostSharp a try. The example on the home page should give an indication how you might use it on a property/method.

Answer 2

No, that's not possible. You will have to do the validation yourself in the setter - just like NotifyPropertyChanged.

Btw - this is called "Aspect Oriented Programming".

Answer 3

As the accepted solution says, it's impossible to do this directly but can be achived by using a tool like PostSharp. Just to add to what's already been told, I wouldn't recommend throwing from a property, or doing validation of this sort on assignment as generally it doesn't hold too much value and can be the cause of some trouble. It may depend on the scenario though.