C#

Ennis Ray Lynch, Jr. wrote:

Objects have to have public, empty constructors to be serialization using the built in methods

Ennis Ray Lynch, Jr. wrote:

Base classes, in general, can't be serialized if they can't be instantiated.

Mark Salsbery
Microsoft MVP - Visual C++

Ennis Ray Lynch, Jr. wrote:

For standard XML serializaiton the default constructor needs to be public

Ennis Ray Lynch, Jr. wrote:

For binary serializaiton you need to have the serialization constructor defined.

Mark Salsbery
Microsoft MVP - Visual C++

public class Foo{

}

public class Foo{
    public Foo(){}
}

public class Foo{
    public Foo(int a){}
}

public class Foo{
    private Foo(){}
}

Ennis Ray Lynch, Jr. wrote:

a default constructor is defined by default unless you create either a non-default constructor or a default constructor with visibility other than public.

Mark Salsbery
Microsoft MVP - Visual C++

	[Serializable]
	public class Animal
	{
		public string str
		{
			get;
			set;
		}
	}

	[Serializable]
	public class Dog : Animal
	{
		[NonSerialized]  <code>//<-- Optional!</code>
		public Int32 A;

		[NonSerialized]  <code>//<-- Optional!</code>
		public Int32 B;

		public Dog()
		{
			A = 5;
			B = 10;
		}
	}

	sealed class DogToAnimalDeserializationBinder : SerializationBinder
	{
		public override Type BindToType(string assemblyName, string typeName)
		{
			Type typeToDeserialize = null;

			String assemVer1 = Assembly.GetExecutingAssembly().FullName;
			String typeVer1 = "Dog";

			if (assemblyName == assemVer1 && typeName == typeVer1)
			{
				typeName = "Animal";
			}

			// The following line of code returns the type.
			typeToDeserialize = Type.GetType(String.Format("{0}, {1}",
				typeName, assemblyName));

			return typeToDeserialize;
		}
	}

...

Dog dog = new Dog();
dog.A = 3;
dog.B = 5;
dog.str = "Animal String";

MemoryStream MemStream = new MemoryStream();

// Serialize a Dog object
BinaryFormatter Serializer = new BinaryFormatter();
Serializer.Serialize(MemStream, dog);

MemStream.Seek(0, SeekOrigin.Begin);

// Deserialize as an Animal object
Serializer.Binder = new DogToAnimalDeserializationBinder();
Animal animal = (Animal)Serializer.Deserialize(MemStream); 

Mark Salsbery
Microsoft MVP - Visual C++

mav.northwind wrote:

The other side of the line (where the object is supposed to be deserialized)
doesn't know about Dogs, it only knows about Animals (i.e. there's
only the assembly defining Animal available, not the one defining Dog,
so trying to deserialize this object will throw a TypeLoadException).

Mark Salsbery
Microsoft MVP - Visual C++