如何升级到 Dart 2？

Question

在我的 macOS 中，我需要安装或升级到 dart 2。但是当我尝试时，我收到了这个错误。请问有什么帮助吗？

$ brew install dart
Warning: dart-lang/dart/dart 1.24.3 is already installed and up-to-date
To reinstall 1.24.3, run `brew reinstall dart`
$ brew install dart --devel
==> Installing dart from dart-lang/dart
Error: dart 1.24.3 is already installed
To upgrade to 2.0.0-dev.63.0, run `brew upgrade dart`
$ brew upgrade dart
Error: dart-lang/dart/dart 1.24.3 already installed
...

Answer 1

这是冈特建议的替代方案。

安装 Dart 2 而不卸载 Dart 1

> brew upgrade dart --devel --force

如果您没有安装 Dart 1，则只需使用：

> brew install dart --devel

在 Dart 1 和 Dart 2 之间切换

要切换到 Dart 1，请使用switch命令，后跟您已安装的 Dart 1 版本。例如：

> brew switch dart 1.24.3

切换回 Dart 2 类似，例如：

> brew switch dart 2.0.0-dev.64.1

列出 Dart 版本

如果您不确定安装了哪个版本的 dart，请运行brew info：

> brew info dart
dart-lang/dart/dart: stable 1.24.3, devel 2.0.0-dev.64.1
The Dart SDK
https://www.dartlang.org/
***[Your locally installed versions of dart will be listed here]*** 

使用dart@2和dart@1公式

在 Dart 2 Final 发布之前，您可以使用酿造公式dart@1，dart@2如下图所示。

警告：这些公式仅限桶，这意味着安装的二进制文件不会以通常的方式进行符号链接。按照命令输出中的说明正确设置 PATH。

> brew install dart@2

==> Installing dart@2 from dart-lang/dart
==> Downloading https://storage.googleapis.com/dart-archive/channels/dev/release/2.0.0-dev.64.1/sdk/dartsdk-macos-x64-release.zip

######################################################################## 100.0%

==> Caveats

Note that this is a prerelease version of Dart.

Please note the path to the Dart SDK:

  /<your-brew-root-path>/opt/dart@2/libexec

This formula is keg-only, which means it was not symlinked into /...,
because this is an alternate version of another formula.

If you need to have this software first in your PATH run:

  echo 'export PATH="/<your-brew-root-path>/opt/dart@2/bin:$PATH"' >> ~/.bash_profile