Extension for class with specific attribute

Question

I would like to have an extension method for any class that has a specific attribute.

For clarification, I have to do my own serialization of objects. But I want to only serialize objects that have this custom attribute. I know I can do it by inheriting from another base class, but I already have the class attribute and I think it would be more elegant, so you could always see if an object is custom serializable.

Something like:

[CustomAttribut]public MyClass{} 

MyClass o = new MyClass() ;
// should only exist if class has attribut CustomAttribut. 
O.CustomSerialize();

I did not find a good solution. Only thing was by inheriting from another class with this extension. — Franki1986
– Franki1986, Commented Jun 3, 2016 at 16:07

Mariusz Jamro · Accepted Answer · 2016-06-03 17:11:00Z

3

Attributes are for storing metadata - values which are static and const and known at compile time. They cannot add methods/fields to your class - interfaces are for doing that. What you can do is to create an interface:

public interface ICustomSerializable{
    string CustomSerialize();
}

Another option is to separate your class from the serialization logic. The serialization would be handled by another class. For example:

public class CustomSerializer{

   public string CustomSerialize(object myObject){
       // for example if object has no CustomAttribut attribute 
       // you can throw "not serializable" exception here.

   }
}

edited Jun 3, 2016 at 17:11

answered Jun 3, 2016 at 16:15

Mariusz Jamro

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2 Comments

Franki1986 Over a year ago

Do you have an example for this with postsharp?

Mariusz Jamro Over a year ago

PostSharp is an overkill in this case (unless you have houndreds of classes annotated with [CustomAttribut] and you know what you're doing)

nvoigt · Accepted Answer · 2016-06-03 16:38:23Z

0

You cannot do that with plain .NET. It's called AOP or Aspect Oriented Programming.

There are a few third party providers, like PostSharp that offer those options.

answered Jun 3, 2016 at 16:38

nvoigt

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1 Comment

Franki1986 Over a year ago

That's unsatisfying, not your answer, thank you for this, I mean that there is a restriction. But I think I will use the Interface, that's ok.

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