Wednesday, August 22, 2012

Dart Lang meeting: All objects hashable, and more

Posted by Bob Nystrom


Here's my notes from this week's Dart language meeting:


Getters and implicit "abstract"

Peter raised an interesting corner case with the new getter syntax and the
optional "abstract" keyword. Given this:

  class Foo {
    get bar;
  }

Does it define an abstract getter "bar" whose type is Dynamic, or a field "bar" whose type is "get"?

Gilad says the grammar isn't actually ambiguous here, so there's no problem. (get bar always defines an abstract getter because the spec disallows "get" as a type name.)

We discussed whether "abstract" should be optional or simply removed. Gilad says we should leave it optional in case people want to use it for emphasis. He also wonders if there's a case we aren't thinking of (maybe like the above?) where having it would be helpful to make something clear.

All objects hashable

This is coming in M1. (Woo!) It's just a matter of implementation. We want this in particular so that closures are hashable.

Doc comments

Lars wants to have the language specify the doc comment syntax so that things like the Editor can parse it. The plan is to go through our existing comments and see what subset of markdown we are actually using in practice and then specify that.

We also would like a doc comment form that works for single-line docs. With lots of short members, it's annoying to have to do:

  /**
   * Tiny comment.
   */
  void tinyMember() => 'blah';

I pointed out that I already borrowed "///" from C# and added support for it in Dartdoc, so they said we'll go with that.

Streaming string interpolation

Lars brought up an issue that he wonders if we'll want language support for at some point. The problem comes when you're getting some recursive structure and stringifying it to a stream. If you use interpolation in that, you can end up back at n^2 complexity.

Should we look into some kind of streaming support for string interpolation? No resolution yet.

Cheers!