Type-forward IsExternalInit on modern .NET.

[teo-tsirpanis]

Fixes compatibility between the .NET Standard 2.0 and modern .NET assemblies.

See Sergio0694/PolySharp#98 (comment) for more details.

[jsquire]

@KrzysztofCwalina, @christothes, @stephentoub: Would appreciate thoughts on this one.

[stephentoub]

@teo-tsirpanis, why? We don't do that in other places, e.g. System.Text.Json has an internal IsExternalInit when built for netstandard2.0 or net462 but doesn't include one when targeting net8.0, net9.0, or net10.0.

[teo-tsirpanis]

System.Text.Json actually does type-forward IsExternalInit on modern frameworks. It needs that because it has one public property with an init; accessor. The OpenAI library does not have a public init; property yet, but once it gets one, it will require type-forwarding IsExternalInit. We can do this now or later.

[stephentoub]

actually does type-forward IsExternalInit

Thanks, I missed we added that.

In what situation do we expect the netstandard asset to be resolved when an app targets net core?

[stephentoub]

Ah, I guess it's the opposite. A netstandard lib is built against this one, and will bake in that reference. Then that netstandard only library gets used on core. OK, this makes sense.

But I'd do it later only if / when it's actually needed; otherwise it's leaking implementation detail.

[jsquire]

Thank you for your contribution, @teo-tsirpanis, and for your interest in improving the OpenAI developer experience.

The OpenAI library does not have a public init; property yet, but once it gets one, it will require type-forwarding IsExternalInit. We can do this now or later.

We avoid init properties as part of the API surface because of these types of corner cases in netstandard2.0 fallbacks. If that's the scenario that is motivating this change, I don't expect that it will be needed.

[jsquire]

Thank you, @teo-tsirpanis, for your contribution and interest in improving the OpenAI developer experience. After discussion between the maintainers and confirming that we have no plans to make use of init properties due to the netstandard2.0 compatibility concerns, I'm going to close this out.