Extensibility problem

[niieani]

@blakeembrey My original typings were contained in a named module, which as I see you've changed to a namespace. This is fine, but now it's impossible to extend the typings (unless I'm unaware of a way?) in an external module.

I'd like to recreate the typings for rethinkdbdash without copy-pasting and having to maintain 2 different versions of the same code. rethinkdbdash simply has a wrapper interface and additionally adds the ability to return Promises from any query (without having to .run()).

Any suggestions?

[blakeembrey]

You should be able to use module augmentation with TypeScript for the use-cases where you would previously have used globals to merge modules.

[niieani]

Yeah, I thought so too. But as soon as I create a module entry to augment the typings, TypeScript starts ignoring the original module. I'll try on a fresh project and see how it goes when I have a bit more time.

[blakeembrey]

It needs a top-level import or export to be considered an "external module" and for augmentation to be valid. Otherwise that same syntax just means "declare module" in a global declaration file. I'll have to test it though.

[ktersius]

Has anyone made progress on how to extend an interface?

As mentioned I'm also using rethinkdbdash and the export interface Run needs to be extended to allow running without a connection but I could not figure out a way that was working.

This is what I tried in it's own d.ts file.

import * as rethinkdb from 'rethinkdb';
import Bluebird = require("bluebird");
declare module "rethinkdb" {
    namespace rethinkdb {
        export interface Run <T> {
            run (connection: Connection, cb: Callback<T>): void;
            run (connection: Connection, options: RunOptions, cb: Callback<T>): void;
            run (connection: Connection, options?: RunOptions): Bluebird<T>;
            run (): Bluebird<T>;
        }
    }
}

[blakeembrey]

@ktersius You will probably need to read some of the TypeScript docs/handbook to get a better understanding of how extending a definition works. There's no namespace rethinkdb and using import at the top-level means this is augmentation (not extension). If you wanted to the old-fashioned global extension you'd need something like:

declare module "rethinkdb" {
    import * as rethinkdb from 'rethinkdb';
    import Bluebird = require("bluebird");

    namespace r {
        export interface Run <T> {
            run (connection: Connection, cb: Callback<T>): void;
            run (connection: Connection, options: RunOptions, cb: Callback<T>): void;
            run (connection: Connection, options?: RunOptions): Bluebird<T>;
            run (): Bluebird<T>;
        }
    }
}

If you want to use augmentation, you need to tweak that slightly.

[blakeembrey]

Actually, I think extending an export = may have some issue still with TypeScript, but I can test that later when I get a chance.

[ktersius]

@blakeembrey Yes using your example gives typings/modules/rethinkdb/index.d.ts(3647,1): error TS2309: An export assignment cannot be used in a module with other exported elements.

[blakeembrey]

@ktersius Remove export from export interface maybe?

[ktersius]

@blakeembrey That has no effect it seems...this is using v 2.0.3 btw.

Still gives:
typings/modules/rethinkdb/index.d.ts(3647,1): error TS2309: An export assignment cannot be used in a module with other exported elements.

declare module "rethinkdb" {
    import * as rethinkdb from 'rethinkdb';
    import Bluebird = require("bluebird");

    namespace r {
        interface Run <T> {
            run (connection: rethinkdb.Connection, cb: rethinkdb.Callback<T>): void;
            run (connection: rethinkdb.Connection, options: rethinkdb.RunOptions, cb: rethinkdb.Callback<T>): void;
            run (connection: rethinkdb.Connection, options?: rethinkdb.RunOptions): Bluebird<T>;
            run (): Bluebird<T>;
        }
    }
}

[ktersius]

@blakeembrey

This seems to do the trick and I can now compile. Although webstorm is completely confused :)
So as I understand this is now using module augmentation?

import * as rethinkdb from 'rethinkdb';
import Bluebird = require("bluebird");
declare module "rethinkdb" {
    namespace r {
        interface Run <T> {
            run (connection: rethinkdb.Connection, cb: rethinkdb.Callback<T>): void;
            run (connection: rethinkdb.Connection, options: rethinkdb.RunOptions, cb: rethinkdb.Callback<T>): void;
            run (connection: rethinkdb.Connection, options?: rethinkdb.RunOptions): Bluebird<T>;
            run (): Bluebird<T>;
        }
    }
}

[blakeembrey]

@ktersius Yes, that would be the preferred way to do it. Then re-export the definition using:

export = rethinkdb

[ktersius]

@blakeembrey Seems it doesn't want the re-export though:
TS2666: Exports and export assignments are not permitted in module augmentations

Otherwise it seems to work fine as far as the compiler is concerned.

Edit: Correction, following compiles.

import * as rethinkdb from 'rethinkdb';
import * as rethinkdbdash from 'rethinkdbdash';
import Bluebird = require("bluebird");
declare module "rethinkdb" {
    namespace r {
        interface Run <T> {
            run (connection: rethinkdb.Connection, cb: rethinkdb.Callback<T>): void;
            run (connection: rethinkdb.Connection, options: rethinkdb.RunOptions, cb: rethinkdb.Callback<T>): void;
            run (connection: rethinkdb.Connection, options?: rethinkdb.RunOptions): Bluebird<T>;
            run(connection: rethinkdb.Connection, options?: rethinkdbdash.RDashConnectionOptions): Bluebird<T>;
            run(options?: rethinkdbdash.RDashConnectionOptions): Bluebird<T>;
        }
    }
}
export = rethinkdb;

[blakeembrey]

Yeah, the correction is the correct way. It's an augmentation, so everything needs to continue being written in external module format. You can then install that definition with Typings or using typeRoots for TypeScript to discover it.

[ktersius]

@blakeembrey Thanks for all your help!

Just posting my tsconfig.json for reference. It doesn't like adding "typeroots" : ["typings", "node_modules/@types"] so I'm using files. Where rethinkdbex/index has the above code.

{
  "compilerOptions": {
    "target": "es6",
    "module": "commonjs",
    "moduleResolution": "node",
    "emitDecoratorMetadata": true,
    "experimentalDecorators": true,
    "allowSyntheticDefaultImports": true,
    "sourceMap": false,
    "inlineSourceMap": true,
    "inlineSources": true,
    "noEmitHelpers": false,
    "strictNullChecks": false,
    "outDir": "./dist",
    "rootDirs": [
      "./src",
      "../shared/src"
    ],
    "baseUrl": "./",
    "paths": {
      "lodash": [
        "node_modules/@types/lodash"
      ],
      "ajv": [
        "node_modules/ajv"
      ]
    }
  },
  "lib": [
    "es6",
    "dom"
  ],
  "files": [
    "typings/modules/rethinkdb/index",
    "typings/modules/rethinkdbdash/index",
    "typings/modules/rethinkdbex/index"
  ],
  "include": [
    "src/**/*"
  ],
  "exclude": [
    "node_modules",
    "dist"
  ],
  "compileOnSave": false,
  "buildOnSave": false
}