导入dart_eval包未调用方法即触发内置代码错误求助

测试代码 #

import 'package:dart_eval/dart_eval.dart';
import 'dart:math';

void main() {
  // print(eval('2 + 2')); // -> 4
  print('hi');
}

错误信息 #

/D:/Flutter%20SDK/flutter/.pub-cache/hosted/pub.dartlang.org/dart_eval-0.6.0/lib/src/eval/shared/stdlib/convert/json.dart:41:13: Error: Expected an identifier, but got ']'.
Try inserting an identifier before ']'.
            ])?.$value;
            ^
/D:/Flutter%20SDK/flutter/.pub-cache/hosted/pub.dartlang.org/dart_eval-0.6.0/lib/src/eval/shared/stdlib/convert/json.dart:41:13: Error: Expected ':' before this.
            ])?.$value;
            ^
/D:/Flutter%20SDK/flutter/.pub-cache/hosted/pub.dartlang.org/dart_eval-0.6.0/lib/src/eval/shared/stdlib/convert/json.dart:40:44: Error: A value of type '$Value' can't be assigned to a variable of type 'bool'.
 - '$Value' is from 'package:dart_eval/src/eval/runtime/class.dart' ('/D:/Flutter%20SDK/flutter/.pub-cache/hosted/pub.dartlang.org/dart_eval-0.6.0/lib/src/eval/runtime/class.dart').
              runtime.wrapPrimitive(value) ?? value as $Value?
                                           ^
/D:/Flutter%20SDK/flutter/.pub-cache/hosted/pub.dartlang.org/dart_eval-0.6.0/lib/src/eval/shared/stdlib/convert/json.dart:104:103: Error: Expected an identifier, but got ']'.
Try inserting an identifier before ']'.
            return toEncodable.call(runtime, null, [runtime.wrapPrimitive(object) ?? object as $Value?])?.$value;
                                                                                                      ^
/D:/Flutter%20SDK/flutter/.pub-cache/hosted/pub.dartlang.org/dart_eval-0.6.0/lib/src/eval/shared/stdlib/convert/json.dart:104:103: Error: Expected ':' before this.
            return toEncodable.call(runtime, null, [runtime.wrapPrimitive(object) ?? object as $Value?])?.$value;
                                                                                                      ^
/D:/Flutter%20SDK/flutter/.pub-cache/hosted/pub.dartlang.org/dart_eval-0.6.0/lib/src/eval/shared/stdlib/convert/json.dart:104:83: Error: A value of type '$Value' can't be assigned to a variable of type 'bool'.
 - '$Value' is from 'package:dart_eval/src/eval/runtime/class.dart' ('/D:/Flutter%20SDK/flutter/.pub-cache/hosted/pub.dartlang.org/dart_eval-0.6.0/lib/src/eval/runtime/class.dart').
            return toEncodable.call(runtime, null, [runtime.wrapPrimitive(object) ?? object as $Value?])?.$value;
                                                                                  ^
/D:/Flutter%20SDK/flutter/.pub-cache/hosted/pub.dartlang.org/dart_eval-0.6.0/lib/src/eval/shared/stdlib/convert/json.dart:171:17: Error: Expected an identifier, but got ']'.
Try inserting an identifier before ']'.
                ])?.$value;
                ^
/D:/Flutter%20SDK/flutter/.pub-cache/hosted/pub.dartlang.org/dart_eval-0.6.0/lib/src/eval/shared/stdlib/convert/json.dart:171:17: Error: Expected ':' before this.
                ])?.$value;
                ^
/D:/Flutter%20SDK/flutter/.pub-cache/hosted/pub.dartlang.org/dart_eval-0.6.0/lib/src/eval/shared/stdlib/convert/json.dart:170:48: Error: A value of type '$Value' can't be assigned to a variable of type 'bool'.
 - '$Value' is from 'package:dart_eval/src/eval/runtime/class.dart' ('/D:/Flutter%20SDK/flutter/.pub-cache/hosted/pub.dartlang.org/dart_eval-0.6.0/lib/src/eval/runtime/class.dart').
                  runtime.wrapPrimitive(value) ?? value as $Value?
                                               ^

已尝试操作 #

• 执行flutter pub upgrade dart_eval，确认dart_eval已是最新的^0.6.0版本

环境配置 #

pubspec.yaml #

name: app
description: A new Flutter project.

publish_to: 'none'

version: 1.0.0+1

environment:
  sdk: '>=2.18.4 <3.0.0'

dependencies:
  flutter:
    sdk: flutter
   
  cupertino_icons: ^1.0.2
  http: ^0.13.5
  dart_eval: ^0.6.0

dev_dependencies:
  flutter_test:
    sdk: flutter 
  
  flutter_lints: ^2.0.0

flutter:

  uses-material-design: true

Flutter Doctor输出 #

[√] Flutter (Channel stable, 3.3.8, on Microsoft Windows [Version 10.0.22621.1555], locale en-US)
    • Flutter version 3.3.8 on channel stable at D:\Flutter SDK\flutter
    • Upstream repository https://github.com/flutter/flutter.git
    • Framework revision 52b3dc25f6 (5 months ago), 2022-11-09 12:09:26 +0800
    • Engine revision 857bd6b74c
    • Dart version 2.18.4
    • DevTools version 2.15.0

[X] Android toolchain - develop for Android devices
    X Unable to locate Android SDK.
      Install Android Studio from: https://developer.android.com/studio/index.html
      On first launch it will assist you in installing the Android SDK components.
      (or visit https://flutter.dev/docs/get-started/install/windows#android-setup for detailed instructions).
      If the Android SDK has been installed to a custom location, please use
      `flutter config --android-sdk` to update to that location.


[√] Chrome - develop for the web
    • Chrome at C:\Program Files\Google\Chrome\Application\chrome.exe

[X] Visual Studio - develop for Windows
    X Visual Studio not installed; this is necessary for Windows development.
      Download at https://visualstudio.microsoft.com/downloads/.
      Please install the "Desktop development with C++" workload, including all of its default components

[!] Android Studio (not installed)
    • Android Studio not found; download from https://developer.android.com/studio/index.html
      (or visit https://flutter.dev/docs/get-started/install/windows#android-setup for detailed instructions).

[√] VS Code (version 1.77.3)
    • VS Code at C:\Users\hanno\AppData\Local\Programs\Microsoft VS Code
    • Flutter extension version 3.62.0

[√] Connected device (3 available)
    • Windows (desktop) • windows • windows-x64    • Microsoft Windows [Version 10.0.22621.1555]
    • Chrome (web)      • chrome  • web-javascript • Google Chrome 112.0.5615.86
    • Edge (web)        • edge    • web-javascript • Microsoft Edge 112.0.1722.39

[√] HTTP Host Availability
    • All required HTTP hosts are available

! Doctor found issues in 3 categories.

问题询问 #

该错误是否与Flutter环境相关？如何解决以在Flutter应用中正常使用dart_eval包？

解决方案 #

这些错误是dart_eval 0.6.0版本内部代码的语法和类型不兼容问题，和你当前的Dart版本（2.18.4）有关，并非Flutter环境本身的问题，可通过以下方式解决：

1. 升级dart_eval到预发布版本
   在pubspec.yaml中将dart_eval依赖改为预发布版本，比如：

   dart_eval: ^0.7.0-dev.1
   

   预发布版本通常修复了旧版本的兼容性问题，适配更高版本的Dart语法。

2. 升级Flutter到较新稳定版
   当前你使用的Flutter 3.3.8对应Dart 2.18.4，版本较旧。升级到Flutter 3.10+稳定版（对应Dart 3.0+），新版本的Dart语法解析更完善，能兼容dart_eval 0.6.0的代码写法。

3. 手动修复dart_eval包内的错误
   若暂时无法升级环境，可手动修改缓存中的dart_eval代码：

   • 打开报错的json.dart文件，将类似[runtime.wrapPrimitive(value) ?? value as $Value?]的代码，改为[(runtime.wrapPrimitive(value) ?? value as $Value?)]，用括号包裹??表达式，解决语法解析错误；
   • 针对类型不匹配问题，将runtime.wrapPrimitive(value) ?? value as $Value?改为runtime.wrapPrimitive(value) as $Value? ?? value as $Value?，统一两边的类型为$Value?。

内容的提问来源于stack exchange，提问作者Hannon qaoud