Remove ISchema in FakeSchema

[wschin]

FakeSchema is not longer an ISchema and renamed to FakeSchemaFactory. It's a part of #1501.

[TomFinley]

FakeSchemaFactory [](start = 26, length = 17)

So @wschin, could we even just do away with most of this code altogether, and just have this be a static class with a single static method? I'm not sure what purpose creating this object actually serves, since you don't actually do anything with the instance per se. So why keep the type, when we can just nuke it?

I'm not even sure if there's some set of utilities for doing stuff with SchemaShape that we could exploit and just put it there.

[sfilipi]

Maybe Schema definition? that has another Create method, creates from a type.

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In reply to: 241493306 [](ancestors = 241493306)

[wschin]

It's a fully-static class now. On the other hand, I don't see another utility function creating Schema out of SchemaShape, so let's keep it for now.

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In reply to: 241493306 [](ancestors = 241493306)

[TomFinley]

Yes -- though creating a SchemaShape out of a Schema is a generally useful utility, the utility of making "fake" schemas out of SchemaShape is somewhat limited, and I think probably something that will eventually go away as we convert things away from the old IDataLoader and IDataTransform idioms.

[TomFinley]

Thanks @wschin , just a few things to consider to simplify further, since I don't see that there's any need for this type to really exist at all, but since it's internal I'm not sure it's such a bit deal. (Just in case you wanted to do something with this in your copious spare time. 😄 )

[sfilipi]

can they be defined inside the method? they are only called once.

[TomFinley]

I don't think so, not while having Utils.MarshalInvoke work (which is a very good thing).

[wschin]

Yeah, I actually tried at least 5 different combinations and googled for several hours.

More specifically, as we need a generic-typed function to invoke, we need to have seperated functions for appending Type parameter. It's possible to have things like

Func<Delegate> act = () => (ValueGetter<VBuffer<TValue>>) ((ref VBuffer<TValue> value) => value = new VBuffer<TValue>(AllVectorSizes, 0, null, null));

in

        public static Schema Create<TValue>(SchemaShape shape)
        {
            var builder = new SchemaBuilder();

            for (int i = 0; i < shape.Count; ++i)
            {
                var metaBuilder = new MetadataBuilder();
                var partialMetadata = shape[i].Metadata;
                for (int j = 0; j < partialMetadata.Count; ++j)
                {
                    var metaColumnType = MakeColumnType(partialMetadata[i]);

                    Delegate del;
                    if (metaColumnType.IsVector)
                    {
                        Func<Delegate> act = () => (ValueGetter<VBuffer<TValue>>) ((ref VBuffer<TValue> value) => value = new VBuffer<TValue>(AllVectorSizes, 0, null, null));
                        del = Utils.MarshalInvoke(act, metaColumnType.ItemType.RawType);
                    }
                    else
                        del = Utils.MarshalInvoke(GetDefaultGetter<int>, metaColumnType.RawType);
                    metaBuilder.Add(partialMetadata[j].Name, metaColumnType, del);
                }
                builder.AddColumn(shape[i].Name, MakeColumnType(shape[i]));
            }
            return builder.GetSchema();
        }

but the user now needs to do Create<int> instead of Create.

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In reply to: 241524344 [](ancestors = 241524344)

[sfilipi]