Exception on attempt to serialize with an interface property about msgpack-cli HOT 6 CLOSED

@amirabiri
Thank you nice feedback.

As you guess, serializing interfaces or abstract classes are problematic because serializer cannot determine what type should be used to deserialize object. MessagePack stream itself does not contain any information of original type.
However your suggestion that serializers fall back to default generic collection implementation for abstract collection types is useful solution.

So, may I ask you a question?

I have two options to implement your idea, which one is preferred do you think?:

1. Register default implementation to SerializationRepository, and ALL serializers refer them.
2. Annotate individual properties with a custom attribute (it might be MessagePackMemberAttribute) to specify default implementation.

from msgpack-cli.

I think there should always be a non-attribute way since attributes are still somewhat invasive.

I would go with both options - configurable defaults in the context options, with the basic collection already configured + ability to override concrete type on a per-property basis using attributes.

For the basic pre-set collections I would support IList, IList<>, IDictionary, IDictionary<>. I'm not sure I would bother with the rest as they are not common data-object paradigms, and if the user can always add them to the context I think that's enough.

from msgpack-cli.

Thank you amirabiri.

I will go with pre-set collections in the context options, and will not support individual properties directly because specifying special concrete types is not very common. Instead, you have already have following work arounds:

1. Make the property/field read-only and instantiate concrete object on constructor/initializer. MessagePack for CLI supports such properties (just call Add(T) method of it instead of assign collection itself).
2. Implements IUnpackable or custom serializer to support special types.

Here is an example of option 1:

public class Foo
{
    private readonly IList<int> _list = new Collection<int>();
    public IList<int> List{ get { return _list; } }
}

What do you think about it?

from msgpack-cli.

I think it's good.

A side note - you should make sure the user can specify generic classes without arguments, i.e so that one can register a custom handler for IList<> rather than IList<string>. Note that you can't do that with a simple Register<> because in such a case the user must specify all type arguments, but with Register(Type type) you can, because you can do Register(typeof(IList<>)), but you can't do Register<IList<>>().

from msgpack-cli.

Thank you. I will design and implement it with your side note in mind.

from msgpack-cli.

I added this feature to 0.4 release.

from msgpack-cli.