Redis: UniversalClient and WithContext

[NathanBaulch]

I understand that Go's lack of return value covariance makes adding WithContext to UniversalClient difficult even though all three client implementations support it.
I'm just wondering if there's a recommended workaround for those of us that want the flexibility of the universal interface but still need context for logging/instrumentation reasons?

FYI, my current workaround:

var (
    contextType         = reflect.TypeOf((*context.Context)(nil)).Elem()
    universalClientType = reflect.TypeOf((*UniversalClient)(nil)).Elem()
)

func WithContext(ctx context.Context, uc UniversalClient) UniversalClient {
    switch uc := uc.(type) {
    case *Client:
        return uc.WithContext(ctx)
    case *ClusterClient:
        return uc.WithContext(ctx)
    case *Ring:
        return uc.WithContext(ctx)
    case interface{ WithContext(context.Context) UniversalClient }:
        return uc.WithContext(ctx)
    default:
        if fn := reflect.ValueOf(uc).MethodByName("WithContext"); fn.IsValid() {
            fnType := fn.Type()
            if fnType.NumIn() == 1 && fnType.NumOut() == 1 &&
                fnType.In(0).Implements(contextType) &&
                fnType.Out(0).Implements(universalClientType) {
                args := []reflect.Value{reflect.ValueOf(ctx)}
                return fn.Call(args)[0].Interface().(UniversalClient)
            }
        }
        panic("not supported")
    }
}

[vmihailenco]

I am not aware of any good workarounds - my intention is to change go-redis and pass context.Context as first argument in v8. This way WithContext becomes less important but you will have to always pass context.Context.