[Feature Request] Improve TypeScript generator

[MrFoxPro]

I believe output like with ts-proto when it's possible to encode plain objects would be much beter then using classes:

message ImageEditDescriptor {
	oneof type {
		bytes replacement = 1;
		string key = 2;
	}
}

output ts:

export interface ImageEditDescriptor {
  type?: { $case: "replacement"; replacement: Uint8Array } | { $case: "key"; key: string } | undefined;
}
export const ImageEditDescriptor = {
  encode(message: ImageEditDescriptor, writer: _m0.Writer = _m0.Writer.create()): _m0.Writer {
    switch (message.type?.$case) {
      case "replacement":
        writer.uint32(10).bytes(message.type.replacement);
        break;
      case "key":
        writer.uint32(18).string(message.type.key);
        break;
    }
    return writer;
  },

  decode(input: _m0.Reader | Uint8Array, length?: number): ImageEditDescriptor {
    const reader = input instanceof _m0.Reader ? input : _m0.Reader.create(input);
    let end = length === undefined ? reader.len : reader.pos + length;
    const message = createBaseImageEditDescriptor();
    while (reader.pos < end) {
      const tag = reader.uint32();
      switch (tag >>> 3) {
        case 1:
          if (tag !== 10) {
            break;
          }

          message.type = { $case: "replacement", replacement: reader.bytes() };
          continue;
        case 2:
          if (tag !== 18) {
            break;
          }

          message.type = { $case: "key", key: reader.string() };
          continue;
      }
      if ((tag & 7) === 4 || tag === 0) {
        break;
      }
      reader.skipType(tag & 7);
    }
    return message;
  },

  create<I extends Exact<DeepPartial<ImageEditDescriptor>, I>>(base?: I): ImageEditDescriptor {
    return ImageEditDescriptor.fromPartial(base ?? ({} as any));
  },
  fromPartial<I extends Exact<DeepPartial<ImageEditDescriptor>, I>>(object: I): ImageEditDescriptor {
    const message = createBaseImageEditDescriptor();
    if (
      object.type?.$case === "replacement" &&
      object.type?.replacement !== undefined &&
      object.type?.replacement !== null
    ) {
      message.type = { $case: "replacement", replacement: object.type.replacement };
    }
    if (object.type?.$case === "key" && object.type?.key !== undefined && object.type?.key !== null) {
      message.type = { $case: "key", key: object.type.key };
    }
    return message;
  },
};

[ma2bd]

In which way is it better? Performance?

[MrFoxPro]

In which way is it better? Performance?

Maybe a little, but main point is it's way more convinient to use. Let's say we want to encode ComplexStruct

struct SimpleStruct {
	a: u32,
	b: String,
}
enum MultiEnum {
	VariantA(i32),
	VariantB(String),
	VariantC { x: u8, y: f64 },
	UnitVariant, // Unit variant added
}
struct UnitStruct;
struct NewtypeStruct(i32);
struct TupleStruct(i32, f64, String);
struct ComplexStruct {
	flag: bool,
	inner: SimpleStruct,
	items: Vec<MultiEnum>,
	unit: UnitStruct,
	newtype: NewtypeStruct,
	tuple: TupleStruct,
	map: HashMap<i32, i64>
}

from Rust to TypeScript.
With #46, we can do it like this:

import * as Registry from "./bincode/registry.ts" // generated file
const ComplexStruct_obj: Registry.ComplexStruct = { // using it as Type
	inner: { a: 42, b: "Hello" },
	flag: true,
	items: [
		{ $: "VariantA", VariantA: 10 },
		{ $: "VariantB", VariantB: "World" }
	],
	unit: null,
	newtype: 99,
	tuple: [123, 45.67, "Test"],
	map: new Map().set(3, 7n)
}
const encoded = Registry.ComplexStruct.encode(ComplexStruct_obj) // using object CompexStruct

We can also in some code use only type imports:
import { type ComplexStruct } from "./bincode/registry.ts"

This is way more convinient than writing new ComplexStruct(..., new MultiEnumVariantC(... new X(..., new Y(), ...)), ...) and so on.