例如，<a href="https://docs.python.org/zh-cn/3/tutorial/inputoutput.html#reading-and-writing-files" class="external-link" target="_blank">你可以使用`with`读取文件</a>：

```Python
with open("./somefile.txt") as f:
    contents = f.read()
    print(contents)
```

在底层，`open("./somefile.txt")`创建了一个被称为"上下文管理器"的对象。

当 `with` 代码块结束时，它会确保关闭文件，即使发生了异常也是如此。

当你使用 `yield` 创建一个依赖项时，**FastAPI** 会在内部将其转换为上下文管理器，并与其他相关工具结合使用。

		return nil, BucketRemoteTargetNotFound{Bucket: bucket}
	}
	if reloaded {
		globalBucketTargetSys.set(bucket, meta)
	}
	return meta.bucketTargetConfig, nil
}

// GetConfigFromDisk read bucket metadata config from disk.
func (sys *BucketMetadataSys) GetConfigFromDisk(ctx context.Context, bucket string) (BucketMetadata, error) {
	objAPI := newObjectLayerFn()
	if objAPI == nil {

pkg archive/zip, method (*Writer) Copy(*File) error
pkg archive/zip, method (*Writer) CreateRaw(*FileHeader) (io.Writer, error)
pkg compress/lzw, method (*Reader) Close() error
pkg compress/lzw, method (*Reader) Read([]uint8) (int, error)
pkg compress/lzw, method (*Reader) Reset(io.Reader, Order, int)
pkg compress/lzw, method (*Writer) Close() error
pkg compress/lzw, method (*Writer) Reset(io.Writer, Order, int)

The build cache has anonymous read access, so you don't need to authenticate in order to use it. You can use a different build cache node by specifying `-DcacheNode=us` for a build cache node in the US or `-DcacheNode=au` for a build cache node in Australia.

	}
	meshConfigMap, err := client.Kube().CoreV1().ConfigMaps(ctx.IstioNamespace()).Get(context.TODO(), meshConfigMapName, metav1.GetOptions{})
	if err != nil {
		return nil, fmt.Errorf("could not read valid configmap %q from namespace %q: %v - "+
			"Use --meshConfigFile or re-run "+command+" with `-i <istioSystemNamespace> and ensure valid MeshConfig exists",
			meshConfigMapName, ctx.IstioNamespace(), err)
	}

actions: # - "s3:CreateBucket" # - "s3:DeleteBucket" # - "s3:GetBucketLocation" # - "s3:ListBucket" # - "s3:ListBucketMultipartU" ## readonlyexamplepolic policy grants access to buckets with name starting with example. ## In addition, grants objects read permissions on buckets starting with example. # - name: readonlyexamplepolic # statements: # - resources: # - 'arn:aws:s3:::example*/*' # actions: # - "s3:GetObject" # - resources: # - 'arn:aws:s3:::example*' # actions: # - "s3:GetBucketLocation" #...

actions: # - "s3:CreateBucket" # - "s3:DeleteBucket" # - "s3:GetBucketLocation" # - "s3:ListBucket" # - "s3:ListBucketMultipartU" ## readonlyexamplepolic policy grants access to buckets with name starting with example. ## In addition, grants objects read permissions on buckets starting with example. # - name: readonlyexamplepolic # statements: # - resources: # - 'arn:aws:s3:::example*/*' # actions: # - "s3:GetObject" # - resources: # - 'arn:aws:s3:::example*' # actions: # - "s3:GetBucketLocation" #...

  // QPS from loadbalancer running outside of cluster).
  // +optional
  optional ExternalMetricSource external = 5;
}

// MetricStatus describes the last-read state of a single metric.
message MetricStatus {
  // type is the type of metric source.  It will be one of "ContainerResource",
  // "External", "Object", "Pods" or "Resource", each corresponds to a matching field in the object.

}

// NonResourceRule holds information that describes a rule for the non-resource
message NonResourceRule {
  // Verb is a list of kubernetes non-resource API verbs, like: get, post, put, delete, patch, head, options.  "*" means all.
  repeated string verbs = 1;

  // NonResourceURLs is a set of partial urls that a user should have access to.  *s are allowed, but only as the full,
  // final step in the path.  "*" means all.

    - [Container Images](#container-images-10)
  - [Changelog since v1.28.0](#changelog-since-v1280)
  - [Urgent Upgrade Notes](#urgent-upgrade-notes)
    - [(No, really, you MUST read this before you upgrade)](#no-really-you-must-read-this-before-you-upgrade)
  - [Changes by Kind](#changes-by-kind-10)
    - [Deprecation](#deprecation)
    - [API Change](#api-change-3)
    - [Feature](#feature-8)