[API Proposal]: Add indexer to record

[Mr0N]

Background and motivation

I suggest adding an indexer to the record for all fields so that the runtime can automatically generate code for it, similar to how it is done for ToString

API Proposal

    public record JsonSaveModel
    {
        public object this[string obj]
        {
            set {
                if (obj == nameof(index))
                    index = value;
                throw new Exception();
            }
            get {
                if (obj == nameof(index))
                    return index;
                throw new Exception();
            }
        }
      
        public string index { get; set; }
}

API Usage

 class Q
    {
        public Q()
        {
            var res = new JsonSaveModel();
            res["index"] = "90239023";
        }
    }

Alternative Designs

No response

Risks

No response

[hez2010]

This should be a language proposal instead of an API proposal.

[HaloFour]

This sounds like a good use case for a source generator. I don't think indexers as you've described would be a generally desirable feature.

[Mr0N]

Due to the not very high speed of reflection, it seems to me that such a function will sometimes be useful

[CyrusNajmabadi]

A source generator does not need reflection (either to function, or for the code it generates :)). This would just generate a switch for you that would allow you to lookup members in the type by their string name :)

[Mr0N]

I have to write a source generator for each project. It's easier to write the indexer manually

[CyrusNajmabadi]

@Mr0N you write the source generator once. Then you can use it in every project.

[Serdan]

@Mr0N https://github.com/Serdan/RecordIndexerGenerator

I won't maintain it, but that should get you started. I've prepared it for publication on nuget as well. Just build and upload the package.

[Mr0N]

I've almost finished the project with indexers, and the ChatGPT indexer wrote to me. I wrote it this way for the future; it might be useful to someone because reflection doesn't work in all cases. Okay, if you ever want to do it.

[Mr0N]

Something like this is happening with the indexer in the records