Update to latest .Hosting beta forces ICommandHandler implementation change

[ErikEJ]

2.0.0-beta4.22272.1

Must add this now - was that intended?

 public int Invoke(InvocationContext context) => throw new NotImplementedException();

[WeihanLi]

The same problem met

[jonsequitur]

Could you expand on the example? What was the code you were using before and what do you need to do now?

[WeihanLi]

Hi @jonsequitur , since there's a new method int Invoke(InvocationContext context) added for ICommandHandler in beta4

• v2.0.0-beta3.22114.1...2.0.0-beta4.22272.1#diff-4225799b1e51b4a76969e695462201a528767f8d5c66948d59916a5029b68d98
• v2.0.0-beta3.22114.1...2.0.0-beta4.22272.1#diff-a36c7b11d9c1d0036406fa22d0442bb71aa978c06b273fa422eb187390d2b467

when we upgrade the package from beat3 to beta4, had to implement this new method to fix the build error.

If it's really necessary to add it, maybe the default interface implement could help avoid breaking changes, maybe likes follows:

public interface ICommandHandler
{
    int Invoke(InvocationContext context) => InvokeAsync(context).GetAwaiter().GetResult();
    // ...
}

[jonsequitur]

This is a great suggestion. We're not too concerned about breaking changes since we're still in beta, but this would also make it easier for people to do the right thing when implementing this interface.

[KalleOlaviNiemitalo]

Cannot use default interface methods on .NET Standard 2.0 though.

[KalleOlaviNiemitalo]

Now that interface ICommandHandler has been replaced with class CliAction in #2095, it would be possible to make either Invoke or InvokeAsync virtual rather than abstract, without using interface default methods and breaking compatibility with .NET Framework. Not both though… but how about this

public abstract class CliAction {
    public abstract int Invoke(ParseResult parseResult);
    public abstract Task<int> InvokeAsync(ParseResult parseResult, CancellationToken cancellationToken);

    // new stuff
    protected async Task<int> InvokeAsyncOverSync(ParseResult parseResult, CancellationToken cancellationToken) => this.Invoke(parseResult);
    protected int InvokeSyncOverAsync(ParseResult parseResult) => this.InvokeAsync(parseResult, CancellationToken.None).GetAwaiter().GetResult();
}

so application-defined actions could then call those methods

internal sealed class AppAction : CliAction {
    public override int Invoke(ParseResult parseResult) {
        …
    }
    
    public override Task<int> InvokeAsync(ParseResult parseResult, CancellationToken cancellationToken) => this.InvokeAsyncOverSync(parseResult, CancellationToken);
}

[KalleOlaviNiemitalo]

Could be considered a duplicate of #1934.