Skip to main content

Dec 3 language design meeting notes (Mixins)



Dart engineer Bob Nystrom has posted the notes from the December 3rd language design meeting. He writes:

If you're as excited about mixins as I am, you'll be happy. This week's language meeting was all about them. I tried to keep up as best as I could this week, but I'm not much of a secretary. Any omissions or mistakes are all my fault.

Lots of people were in this meeting. Except Lars, who is apparently in Austria with Katy Perry. I'm guessing that's a joke, but you can never tell...

Kasper likes the proposal but discussed some syntax changes with Peter.

They are discussing VM implementation since Ivan [VM lead] is in Aarhus [Kasper and Lars' office]. Does the mixin have to go in the superclass chain?

Gilad: There is well-defined semantic model and it has been implemented before.

Kasper: Where is it being in superclass chain visible? Reflection?

Gilad: In is checks too. You could also see it in super calls, but the current proposal says you can't have those.

Kasper: But the class mixing it in can have super calls.

Gilad: Yes, and there you should see mixin methods.

Kasper: Would a super in a class that extends a mixin application hit the superclass or the mixed in methods?

Gilad: Would hit superclass, which is mixed in methods.

Kasper: If you want to override a mixed in method...

Gilad: Yes, need to have same rules for how an override works.

Ivan: I thought a super call skips mixins and goes straight to class in extends clause.

Gilad: That's not the original intent. "Goes to superclass" means "go to the superclass which *is* the compound mixin application class".

Ivan: I thought it was more complicated then because you have to skip these other artificially created superclasses.

[More discussion here, the end result of which, I think is that this is easier to implement than Ivan originally thought.]

Kasper: Is it OK to canonicalize mixin applications?
Ivan: Is it legal to canonicalize but not forced?

Ivan is worried about class explosion. Gilad says he hasn't seen that in other languages.

I pointed out that we're doing more code generation like in web components, so there may be more artifically generated classes and mixins.

Kasper: I'm not too worried about canonicalization. It probably wouldn't be a breaking change if we changed it.

Ivan: I'd be more comfortable if it allowed but did not mandate it.

Kasper: The next step from my POV is agreeing on syntax.

Cheers!

As always, we invite you to join our Dart mailing list, ask questions on Stack Overflow, or file feature requests on dartbug.com.

Photo credit: http://arlingtonhousewife.files.wordpress.com/2010/08/batter-without-mixins.jpg

Popular posts from this blog

Dart in 2016: The fastest growing programming language at Google, 2nd fastest growing in TIOBE Index

Dart was the fastest growing programming language at Google in 2016 with millions of lines of code written. It also made it to TIOBE Index Top 20 this month (see TIOBE's methodology).

It takes time to build something as ambitious as Dart and, in some ways, Dart is still in its infancy. But we're glad the hard work is starting to pay off.

Many thanks to our amazing community!

We're going to celebrate by ... releasing 1.22 next week (as per our usual 6 week release schedule).

A stronger Dart for everyone

We are constantly asking ourselves:
How do we make developers even more productive when writing Dart apps? We believe that a critical part of the answer to this question is to make strongmode – a sound static type system for Dart – the standard for all Dart developers.

Teams that use Dart to build apps like Soundtrap, AdWords, AdSense, and Greentea say they really enjoy using strong mode features, such as early error detection. In fact, teams that have switched completely to strong mode cite not only early error detection but also better code readability and maintainability as major benefits. We hear this both from small teams and – even more so – from large teams with hundreds of developers writing and maintaining millions of lines of Dart code. As Björn Sperber from Soundtrap says,
Strong mode and the smooth integration with IntelliJ is a joy to use and a huge improvement. If you’ve tried out Flutter, you’ve already used strong mode checks from the Dart analyzer.

Given the benefits …

AngularDart 3.0: Easy upgrade, better performance

AngularDart 3.0 is now available. It brings better performance and smaller generated code, while also making you more productive.


Version 3.0 is an evolution: although it has some breaking changes (detailed below), it is a smooth upgrade due to minimal public API adjustments. Most of the progress is under the hood—in code quality, stability, generated code size, performance, and developer experience.

Code quality:
2731 instances of making the framework code more type safe (using sound Dart).The AngularDart framework code size is down by 12%.Many additional style updates to the codebase:Changed to use idiomatic <T> for generic methods.Removed NgZoneImpl, all the code exists in NgZone now.Stability:
Many CSS encapsulation fixes due to update with csslib package.Fixed bugs with IE11.

Performance:
For the Mail sample app, we see 30% faster time-to-interactive (currently 3812 ms on a simulated 3G connection, measured via Lighthouse).Our large app benchmark shows 2x faster render times of…