Will the VB.Net Serializers execute code in public members?

Question

We wish to use the Binary Formatter. In debugging, thus far, it seems that it does not execute the getters for public properties. Does the XML Serializer behave the same way? Also, during deserialization, will the deserializers use the setters to apply the values during deserialization?

Thus far, our testing with BinaryFormatter shows that it simply writes directly to and from member variables. It does not step through any of the getters or setters. Is the XML Serializer the same way?

What if a public property did something silly like Random().Next? Will this be serialized by the Binary Formatter? It seems that with the XML Serializer, you would need to decorate this member appropriately to get it to participate. The Binary Formatter seems to only work, again, on member variables.

Thanks.

Answer 1

You need both a getter and a setter or the property will not be serialized. The reason for this is that the serializer assumes it can't set the value so transporting it would be wasteful.

You can even have an empty setter and it will work.

Answer 2

Think about it this way:

Let's say you're deserializing a class with several serialized properties, and the setter for the last property has side effects that can alter the values of another property. The altered property no longer reflects your serialized data. Do you really want it to use that setter?

On the other hand, what if there is no backing store for a property? Perhaps it's a composite property allowing you to get and set values of all the others at once. Arguably this property shouldn't be serialized (or only this property should be serialized, depending on how things work), but there could be other examples. How does the formatter know where to assign the value for such a property?

So which is it? I had to look it up and couldn't quickly find an authoritative source, but it looks like the XmlSerializer does use getters and setters while the BinaryFormatter does not use getters or setters.

And that kind of makes sense. My first point showed that you don't really want to use getter/setters. My 2nd point showed that you may have to use them. The binary formatter can just take the exact in-memory representation of the object, so it skips the getter/setters. The XmlSerializer, which doesn't have this ability, has to use the other method.

You should probably set up a quick test project for yourself so you can see it in action.

Answer 3

I just ran a quick test using the XML Serializer. To answer your question: Yes, it does use the getters durning serialization and it does use the setters during deserialization.

EDIT

Found this in the docs:

This example uses a binary formatter to do the serialization. All you need to do is create an instance of the stream and the formatter you intend to use, and then call the Serialize method on the formatter. The stream and the object to serialize are provided as parameters to this call. Although it is not explicitly demonstrated in this example, all member variables of a class will be serialized—even variables marked as private. In this aspect, binary serialization differs from the XMLSerializer Class, which only serializes public fields. For information on excluding member variables from binary serialization, see Selective Serialization.