小编Jua*_*nRO的帖子

导入错误：无法从“botocore.docs.bcdoc”
（/python3.7/site-packages/botocore/docs/bcdoc/ init .py）导入名称“docevents”

Traceback (most recent call last):
  File "/root/.pyenv/versions/3.7.6/bin/aws", line 19, in <module>
    import awscli.clidriver

  File "/root/.pyenv/versions/3.7.6/lib/python3.7/site-packages/awscli/clidriver.py", line 36, in <module>
    from awscli.help import ProviderHelpCommand

  File "/root/.pyenv/versions/3.7.6/lib/python3.7/site-packages/awscli/help.py", line 23, in <module>
    from botocore.docs.bcdoc import docevents

ImportError: cannot import name 'docevents' from 'botocore.docs.bcdoc' (/root/.pyenv/versions/3.7.6/lib/python3.7/site-packages/botocore/docs/bcdoc/__init__.py)

[Container] 2020/10/29 16:48:39 Command did not exit successfully aws --version exit status 1

失败发生在PRE_BUILD 中。

这是我的规范构建文件：buildspec-cd.yml

pre_build:
    commands:
      - AWS_REGION=${AWS_DEFAULT_REGION}
      - COMMIT_HASH=$(echo $CODEBUILD_RESOLVED_SOURCE_VERSION | cut -c 1-7)
      - IMAGE_VERSION=${COMMIT_HASH}
      - REPOSITORY_URI=${CONTAINER_REGISTRY}/${APPLICATION_NAME}
      - …

为什么我不能在条件运算符中返回具有共同祖先的兄弟类型？

为什么C#不支持这个？

class Polygon
{
    public int CountSides { get; set; }
}

class Rectangle : Polygon { }

class Circle : Polygon { }

class Program
{
    static void Main(string[] args)
    {
        Polygon p = true ? new Circle() : new Rectangle();
    }
}