Platform Agnostic Types (with extensions to wrap)

[jtmcdole]

Background: While writing Dart frontend and backend code, I've found it nice to have the core of my server's logic be non-"dart:io" - allowing me to have a better integration testing story and a "run everything in the browser" story (e.g. https://jtmcdole.github.io/auth_simulator/).

What I'm missing most of the time is platform agnostic versions of the following types:

• HttpStatus
• HttpHeader
• ContentType

Along with any extensions to convert platform-specific classes to package:http classes (request/response).

e.g.:

• Cocoon (Flutter's infra orchestrator) runs on AppEngine.
  • Wraping request in native flow https://github.com/flutter/cocoon/pull/4961/changes#diff-2da025aac2cb44f320bb7f5a8d935736504c1f5e298072b11e1d28ac4a8fc63f
  • The extension to convert: https://github.com/flutter/cocoon/blob/8009533d42f8b37c2250ca30103de6460b1d4e7d/app_dart/lib/src/request_handling/http_io.dart#L4
  • And the other classes: https://github.com/flutter/cocoon/blob/8009533d42f8b37c2250ca30103de6460b1d4e7d/app_dart/lib/src/request_handling/http_utils.dart

[JaffaKetchup]

I'm in a similar situation, looking also for HttpDate. For packages, these are good ways to keep maintainability without duplicating already written code from the internals out to the package itself.

More specifically, importing these allowed members in a package causes pana to treat the package as non-web & non-WASM compatible. (Whilst web support can be indicated in pubspec, WASM support cannot be).

There was an issue open, dart-lang/site-www#6103, which had these concerns before and suggested a documentation fix - but this isn't totally sufficient as this issue suggests. That issue was closed without action.

I'm not very familiar with the internals/core of Dart here - there seems to be lots of tightly linked libraries between 'dart:_internal', 'dart:_http' and 'dart:core', where these members are exported by none, one, or both of 'dart:io' and 'dart:html'.

Is there a list we can come up with that has all of these actually-web-safe members? Is it as simple as it's everything already exposed in 'dart:_http'?

Where would be the best place to move these whilst causing minimal changes to the core code already in place? Would this be feasibly possible? Or do they just need exposing differently (i.e. not through either io or html)?

[kevmoo]

https://pub.dev/documentation/http_parser/latest/http_parser/MediaType-class.html - This gets you some of the way there!