# Dart Apprentice: Beyond the Basics **URL:** https://forums.kodeco.com/c/books/dart-apprentice-beyond-basics/93.md [Latest](https://forums.kodeco.com/latest.md) · [Categories](https://forums.kodeco.com/categories.md) · [Tags](https://forums.kodeco.com/tags.md) --- ## [Errata for Dart Apprentice: Beyond the Basics 1st Edition](https://forums.kodeco.com/t/errata-for-dart-apprentice-beyond-the-basics-1st-edition/180744)
**Author:** [@jellodiil](https://forums.kodeco.com/u/jellodiil)\ **Replies:** 21\ **Last updated:** [January 31, 2023, 5:16am UTC](https://forums.kodeco.com/t/errata-for-dart-apprentice-beyond-the-basics-1st-edition/180744 "2023-01-31T05:16:47Z")
Creating this topic to catch any typos and bugs in the 1st Edition of Dart Apprentice: Beyond the Basics. --- ## [About the Dart Apprentice: Beyond the Basics category](https://forums.kodeco.com/t/about-the-dart-apprentice-beyond-the-basics-category/180743)
**Author:** [@jellodiil](https://forums.kodeco.com/u/jellodiil)\ **Replies:** 0
This is the official forum for our book, Dart Apprentice: Beyond the Basics, available here: https://www.kodeco.com/books/dart-apprentice-beyond-the-basic --- ## [About Future generic type](https://forums.kodeco.com/t/about-future-generic-type/184765)
**Author:** [@ellery](https://forums.kodeco.com/u/ellery)\ **Replies:** 4\ **Last updated:** [August 4, 2023, 11:08am UTC](https://forums.kodeco.com/t/about-future-generic-type/184765 "2023-08-04T11:08:11Z")
I have a question about the Future generic type below The code in the book is: print('Before the future'); final myFuture = Future\.delayed( Duration(seconds: 1), () =\> 42, ) .then( (value) =\> print(… --- ## [\[share\] verification of await keyword behaviour](https://forums.kodeco.com/t/share-verification-of-await-keyword-behaviour/184784)
**Author:** [@ellery](https://forums.kodeco.com/u/ellery)\ **Replies:** 4\ **Last updated:** [August 4, 2023, 11:05am UTC](https://forums.kodeco.com/t/share-verification-of-await-keyword-behaviour/184784 "2023-08-04T11:05:55Z")
I want to share how I verify the point: everything after await keyword is sent to event queue. When I first come across the code in the book below: Future\ main() async { print('Before the future'); final … --- ## [\[Suggestion\] Explain mixin plus the on keyword](https://forums.kodeco.com/t/suggestion-explain-mixin-plus-the-on-keyword/184460)
**Author:** [@ellery](https://forums.kodeco.com/u/ellery)\ **Replies:** 2\ **Last updated:** [July 31, 2023, 7:38pm UTC](https://forums.kodeco.com/t/suggestion-explain-mixin-plus-the-on-keyword/184460 "2023-07-31T19:38:04Z")
Hi don’t know why I can think of so many questions in this chapter of enhanced enum. About the code of mixin in enhanced enum enum Fruit with Describer { cherry, peach, banana, } enum Vegetable with Describer { … --- ## [About Challenge 2 solution code in Chapter 6 Mixins](https://forums.kodeco.com/t/about-challenge-2-solution-code-in-chapter-6-mixins/183836)
**Author:** [@ellery](https://forums.kodeco.com/u/ellery)\ **Replies:** 2\ **Last updated:** [June 23, 2023, 1:25pm UTC](https://forums.kodeco.com/t/about-challenge-2-solution-code-in-chapter-6-mixins/183836 "2023-06-23T13:25:57Z")
The solution code try to implements Comparable\ My code don’t have the \ type declaration, see below: class Platypus extends Animal with EggLayer implements Comparable { @override void eat() { … --- ## [About fold function in Chapter 2 anonymous function](https://forums.kodeco.com/t/about-fold-function-in-chapter-2-anonymous-function/183226)
**Author:** [@ellery](https://forums.kodeco.com/u/ellery)\ **Replies:** 3\ **Last updated:** [June 26, 2023, 2:17am UTC](https://forums.kodeco.com/t/about-fold-function-in-chapter-2-anonymous-function/183226 "2023-06-26T02:17:08Z")
const evens = \[2, 4, 6, 8, 10, 12\]; final total = evens.fold\( 0, (sum, element) =\> sum + element, ); Hi I don’t quite understand why I need to add \ after fold? What is the implication of it? However, I co… --- ## [\[Share\] Interesting behaviour for mixin](https://forums.kodeco.com/t/share-interesting-behaviour-for-mixin/183803)
**Author:** [@ellery](https://forums.kodeco.com/u/ellery)\ **Replies:** 3\ **Last updated:** [June 19, 2023, 10:15am UTC](https://forums.kodeco.com/t/share-interesting-behaviour-for-mixin/183803 "2023-06-19T10:15:38Z")
Hi I would like to share an interesting behaviour below: See the code: mixin EggLayer { void layEggs() { print('Plop plop'); } } mixin Flyer { void fly() { print('Swoosh swoosh'); } } abstract cla… --- ## [My first few thoughts about record, pattern and class modifier](https://forums.kodeco.com/t/my-first-few-thoughts-about-record-pattern-and-class-modifier/188203)
**Author:** [@ellery](https://forums.kodeco.com/u/ellery)\ **Replies:** 2\ **Last updated:** [June 12, 2023, 7:59am UTC](https://forums.kodeco.com/t/my-first-few-thoughts-about-record-pattern-and-class-modifier/188203 "2023-06-12T07:59:15Z")
Here are some thoughts after reading the documentation, I am not intend to be original and any examples are dedicated to their original authors. Records Reference doc: Records The documentation may be somewhat insuffic… --- ## [Dart 3 Released!](https://forums.kodeco.com/t/dart-3-released/187270)
**Author:** [@ellery](https://forums.kodeco.com/u/ellery)\ **Replies:** 2\ **Last updated:** [June 11, 2023, 3:25pm UTC](https://forums.kodeco.com/t/dart-3-released/187270 "2023-06-11T15:25:17Z")
Dart 3 Released! Dart 3 is released with new flutter version. Quick overview Flutter at Google I/O 2023 in 5 minutes: https://youtu.be/a0Da8TNMTyM Dart new feature blog post: Announcing Dart 3. 100% sound null safety. … --- ## [\[further study\] about flutter development](https://forums.kodeco.com/t/further-study-about-flutter-development/186051)
**Author:** [@ellery](https://forums.kodeco.com/u/ellery)\ **Replies:** 2\ **Last updated:** [April 10, 2023, 9:26am UTC](https://forums.kodeco.com/t/further-study-about-flutter-development/186051 "2023-04-10T09:26:15Z")
Hi, I finally finished everything, taking notes on the book, run the code, do all the challenges, it is a long journey actually. If it is a simple mere reading, the book is not very long. Most of the time is on thinking … --- ## [\[sidetracked topic\] about recursive function](https://forums.kodeco.com/t/sidetracked-topic-about-recursive-function/184086)
**Author:** [@ellery](https://forums.kodeco.com/u/ellery)\ **Replies:** 4\ **Last updated:** [April 8, 2023, 6:27am UTC](https://forums.kodeco.com/t/sidetracked-topic-about-recursive-function/184086 "2023-04-08T06:27:16Z")
Chapter 8 uses recursive function to write a tree. I would like to point out that deep recursive function is an inefficient algorithm and programmer should avoid this. See the following code of calculating n-th Fibonacc… --- ## [About using Stream Controllers to build stream](https://forums.kodeco.com/t/about-using-stream-controllers-to-build-stream/185378)
**Author:** [@ellery](https://forums.kodeco.com/u/ellery)\ **Replies:** 1\ **Last updated:** [March 22, 2023, 8:36am UTC](https://forums.kodeco.com/t/about-using-stream-controllers-to-build-stream/185378 "2023-03-22T08:36:48Z")
Hi About the last part of chapter 13 Streams. The book introduce a method to build a stream from scratch using the StreamController class. The code in main starts with Future\ main() async. Isn’t better just to kee… --- ## [About error handling in stream section](https://forums.kodeco.com/t/about-error-handling-in-stream-section/185029)
**Author:** [@ellery](https://forums.kodeco.com/u/ellery)\ **Replies:** 2\ **Last updated:** [March 14, 2023, 11:20am UTC](https://forums.kodeco.com/t/about-error-handling-in-stream-section/185029 "2023-03-14T11:20:17Z")
About using try-catch approach for error handling in Chapter 13: Streams. The code is: try { final file = File('assets/text\_long.txt'); final stream = file.openRead(); await for (var data in stream) { print(d… --- ## [Why need to use Completer class](https://forums.kodeco.com/t/why-need-to-use-completer-class/184951)
**Author:** [@ellery](https://forums.kodeco.com/u/ellery)\ **Replies:** 2\ **Last updated:** [March 11, 2023, 9:46am UTC](https://forums.kodeco.com/t/why-need-to-use-completer-class/184951 "2023-03-11T09:46:58Z")
About the section Creating a Future From Scratch in Chapter 12 Futures, I just don’t understand why I need to use Completer class to build a Future instance. The code using async keyword just work and very readable: … --- ## [About use of http package in Chapter 12 Futures](https://forums.kodeco.com/t/about-use-of-http-package-in-chapter-12-futures/184909)
**Author:** [@ellery](https://forums.kodeco.com/u/ellery)\ **Replies:** 2\ **Last updated:** [March 9, 2023, 12:10pm UTC](https://forums.kodeco.com/t/about-use-of-http-package-in-chapter-12-futures/184909 "2023-03-09T12:10:43Z")
In Chapter 12 Futures, is http a third party package developed by someone else. Therefore we need to add the line http: ^0.13.5 in the dependencies section in the pubspec.yaml file? This syntax will specify Dart to load… --- ## [Simplify the mixin code of enhanced enum with extension](https://forums.kodeco.com/t/simplify-the-mixin-code-of-enhanced-enum-with-extension/184426)
**Author:** [@ellery](https://forums.kodeco.com/u/ellery)\ **Replies:** 4\ **Last updated:** [February 27, 2023, 5:42am UTC](https://forums.kodeco.com/t/simplify-the-mixin-code-of-enhanced-enum-with-extension/184426 "2023-02-27T05:42:17Z")
Hi I believe that the mixin code in the last part of Chapter 9: enhanced enum can be simplified using an extension: enum Fruit{ cherry, peach, banana, } enum Vegetable{ carrot, broccoli, spinach, } extensi… --- ## [About using Generic in enhanced enum](https://forums.kodeco.com/t/about-using-generic-in-enhanced-enum/184429)
**Author:** [@ellery](https://forums.kodeco.com/u/ellery)\ **Replies:** 1\ **Last updated:** [February 25, 2023, 9:55am UTC](https://forums.kodeco.com/t/about-using-generic-in-enhanced-enum/184429 "2023-02-25T09:55:34Z")
The generic part of the code: enum Default\ { font\('roboto'), size\(17.0), weight\(400); const Default(this.value); final T value; } And I find that it works completely we… --- ## [Simplifying the Day class in enhanced enum chapter](https://forums.kodeco.com/t/simplifying-the-day-class-in-enhanced-enum-chapter/184430)
**Author:** [@ellery](https://forums.kodeco.com/u/ellery)\ **Replies:** 1\ **Last updated:** [February 25, 2023, 9:40am UTC](https://forums.kodeco.com/t/simplifying-the-day-class-in-enhanced-enum-chapter/184430 "2023-02-25T09:40:23Z")
Hi, I find that the Day class code: enum Day { monday, tuesday, wednesday, thursday, friday, saturday, sunday; Day operator +(int days) { final numberOfItems = Day.values.length; final i… --- ## [\[Suggestion\] moving the operator overloading explanation to book 1](https://forums.kodeco.com/t/suggestion-moving-the-operator-overloading-explanation-to-book-1/184432)
**Author:** [@ellery](https://forums.kodeco.com/u/ellery)\ **Replies:** 2\ **Last updated:** [February 25, 2023, 9:36am UTC](https://forums.kodeco.com/t/suggestion-moving-the-operator-overloading-explanation-to-book-1/184432 "2023-02-25T09:36:14Z")
Hi in chapter 9 enhanced enums, I suggest moving the explanation of operator overloading to a suitable place in book1. This is because this is quite similar to method overriding and can be introduced earlier. People can… --- ## [\[fun share\] chatGPT to improve mixin](https://forums.kodeco.com/t/fun-share-chatgpt-to-improve-mixin/183835)
**Author:** [@ellery](https://forums.kodeco.com/u/ellery)\ **Replies:** 6\ **Last updated:** [February 14, 2023, 8:08am UTC](https://forums.kodeco.com/t/fun-share-chatgpt-to-improve-mixin/183835 "2023-02-14T08:08:47Z")
I try to ask chatGPT about improving code using mixin. see below: --- ## [Suggest to improve the challenge in Chapter 4 Abstract class](https://forums.kodeco.com/t/suggest-to-improve-the-challenge-in-chapter-4-abstract-class/183642)
**Author:** [@ellery](https://forums.kodeco.com/u/ellery)\ **Replies:** 2\ **Last updated:** [February 8, 2023, 2:28pm UTC](https://forums.kodeco.com/t/suggest-to-improve-the-challenge-in-chapter-4-abstract-class/183642 "2023-02-08T14:28:25Z")
Just don’t quite understand the purpose of this exercise. Is it the author wants to let us know even concrete class can be declared abstract? Otherwise, I don’t think there is need to declare the parent class as abstract…… --- ## [Gratitude — this is awesome](https://forums.kodeco.com/t/gratitude-this-is-awesome/182956)
**Author:** [@eshfield](https://forums.kodeco.com/u/eshfield)\ **Replies:** 4\ **Last updated:** [February 7, 2023, 10:56pm UTC](https://forums.kodeco.com/t/gratitude-this-is-awesome/182956 "2023-02-07T22:56:45Z")
I want to thank you for the humor in your books and for this episode especially: This is really fun! Thanks for making the learning so amusing :slight\_smile: --- ## [Generic functions signature](https://forums.kodeco.com/t/generic-functions-signature/182986)
**Author:** [@eshfield](https://forums.kodeco.com/u/eshfield)\ **Replies:** 2\ **Last updated:** [January 28, 2023, 12:25pm UTC](https://forums.kodeco.com/t/generic-functions-signature/182986 "2023-01-28T12:25:19Z")
PDF, Chapter 8: Generics, Paragraph Creating Generic Functions → Implementing the Function: Node\? createTree\(…) { … } Can’t figure out where does the \ in the function name createTree\ come from? I didn’t s… --- ## [Regex unexpected value match](https://forums.kodeco.com/t/regex-unexpected-value-match/182912)
**Author:** [@shakirkasmani92](https://forums.kodeco.com/u/shakirkasmani92)\ **Replies:** 5\ **Last updated:** [January 26, 2023, 7:54am UTC](https://forums.kodeco.com/t/regex-unexpected-value-match/182912 "2023-01-26T07:54:46Z")
In string validation exercise credit card number should be number and 16 digit long so I tried Regex1 bool validateCreditCardNumber(String number) { final numbersOnly = RegExp(r'^\[0-9\]+$'); final validLength = Reg…