Chapter 1 - about the file: pubspec.lock & .packages

ellery · May 24, 2022, 9:50am

Hi, I create a Dart project with Dart SDK 2.17.1, there are two more files: 1. pubspec.lock and .package.

Could you also explain briefly what these files are?

robertomachorro · May 24, 2022, 11:20am

lauragales · May 24, 2022, 2:44pm

The .packages file was a Dart Package Configuration File. A new file has replaced it package_config.json now located in .dart_tool subdirectory. The file is generated, not for manual editing. Some information about the file can be found on the following linked page language/package-config-file-v2.md at master · dart-lang/language · GitHub

The lockfile is generated automatically as well, to ensure that you can recreate the exact configuration of packages used by an application. It locks down the version numbers and contains more information than the standard pubspec.

ellery · May 25, 2022, 3:58am

Thank you! I will finish this book asap and then go to learn flutter development.

lauragales · June 8, 2022, 10:55pm

Hope your progressing nicely with the books!

An update to my previous post:
In the upcoming Dart 3.18.0 release, the .packages will no longer be created.

Relevant part from the Dart change log:

dart pub get and dart pub upgrade no longer creates the deprecated .packages file. It can still be created with the --legacy-packages-file flag.

github.com

dart-lang/sdk/blob/main/CHANGELOG.md

## 3.4.0

## 3.3.0

### Language

- **Breaking Change** [#54056][]: The rules for private field promotion have
  been changed so that an abstract getter is considered promotable if there are
  no conflicting declarations (i.e., there are no non-final fields, external
  fields, concrete getters, or `noSuchMethod` forwarding getters with the same
  name in the same library). This makes the implementation more consistent and
  allows type promotion in a few rare scenarios where it wasn't prevoiusly
  allowed. It is unlikely, but this change could in principle cause a breakage
  by changing an inferred type in a way that breaks later code. For example:

  ```dart
  class A {
    int? get _field;
  }
  class B extends A {

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ellery · June 9, 2022, 8:52am

Hi Laura, thank you. I progress slowly on the book. Now, I am reading chapter 4.