Skip to main content

Breaking Change: Iterable.mappedBy is now Iterable.map, List.skip/take return Iterables

mappedBy(), we hardly knew ye!! Florian Loitsch tells us the reason for the name change to map() 

We are reverting the name-change to 'map'. I got a lot of feedback, and the name is clearly not working for most of you. We are therefore reverting back to "map".

In order to avoid mistakes we will also make the return-type (and dynamic type) of List.map be an Iterable, and not a List. This will, hopefully, make it more clear that the result is a lazy wrapper instead of an eager evaluation.

For consistency we changed the return-type of List.skip and List.take to be an Iterable too.

We are going to keep the mappedBy method in the implementation (next to "map") for several weeks, so you have the time to migrate. The List.skip/take methods will furthermore continue to return Lists (even though their return type is "Iterable").

When we finish the transition "mappedBy" will go away, and skip/take will return Iterables (dynamic type) and not Lists anymore.

A patch for this change has already been uploaded, and will be committed soon (probably tomorrow):
https://chromiumcodereview.appspot.com/12086062/.

Since we changed the name in the Iterable, we also changed it in the Stream class. So Stream.mappedBy is now Stream.map.

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

Comments

Post a Comment

Popular posts from this blog

Const, Static, Final, Oh my!

Posted by Seth Ladd

(This is an "oldie but a goodie" misc@dartlang.org post originally written by Bob Nystrom. It is being posted here as the explanations still ring true.)

Bob writes:


"static", "final", and "const" mean entirely distinct things in Dart:

"static" means a member is available on the class itself instead of on instances of the class. That's all it means, and it isn't used for anything else. static modifies *members*.

"final" means single-assignment: a final variable or field *must* have an initializer. Once assigned a value, a final variable's value cannot be changed. final modifies *variables*.

"const" has a meaning that's a bit more complex and subtle in Dart. const modifies *values*. You can use it when creating collections, like const [1, 2, 3], and when constructing objects (instead of new) like const Point(2, 3). Here, const means that the object's entire deep state can be determ…

Dart 1.12 Released, with Null-Aware Operators and more

Dart 1.12.0 is now released! It contains the new null-aware operators language feature, and enhancements to pub, Observatory, dartdoc, and much more.

Null-aware operators

The new null-aware operators help you reduce the amount of code required to work with references that are potentially null. This feature is a collection of syntactic sugar for traversing (potentially null) object calls, conditionally setting a variable, and evaluating two (potentially null) expressions.

Click or tap the red Run button below to see them in action.

??

  if null operator. `expr1 ?? expr2` evaluates to `expr1` if not `null`, otherwise `expr2`.


??=

  null-aware assignment. `v ??= expr` causes `v` to be assigned `expr` only if `v` is `null`.

x?.p

  null-aware access. `x?.p` evaluates to `x.p` if `x` is not `null`, otherwise evaluates to `null`.

x?.m()

  null-aware method invocation. `x?.m()` invokes `m` only if `x` is not `null`.

Learn more about Dart's null-aware operators in our Language Tour.

.packages fi…

The new AdWords UI uses Dart — we asked why

Google just announced a re-designed AdWords experience. In case you’re not familiar with AdWords: businesses use it to advertise on google.com and partner websites. Advertising makes up majority of Google’s revenue, so when Google decides to completely redo the customer-facing front end to it, it’s a big deal. The Dart team is proud to say that this new front end is built with Dart and Angular 2. Whenever you asked us whether Google is ‘even using Dart for anything,’ this is what we had in mind but couldn’t say aloud. Until now. We asked Joshy Joseph, the primary technical lead on the project, some questions. Joshy is focusing on things like infrastructure, application latency and development velocity, so he’s the right person to ask about Dart.Q: What exactly did we launch on Monday?It’s a complete redesign of the AdWords customer experience that is rolling out slowly as a test to a small initial set of advertisers. The most noticeable thing is probably the Material Design look and f…