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)

	}
	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.

---

When building APIs, you normally use these specific HTTP methods to perform a specific action.

Normally you use:

* `POST`: to create data.
* `GET`: to read data.
* `PUT`: to update data.
* `DELETE`: to delete data.

So, in OpenAPI, each of the HTTP methods is called an "operation".

We are going to call them "**operations**" too.

  val ANY_VALUE =
    object : DerAdapter<AnyValue> {
      override fun matches(header: DerHeader): Boolean = true

      override fun fromDer(reader: DerReader): AnyValue {
        reader.read("ANY") { header ->
          val bytes = reader.readUnknown()
          return AnyValue(
            tagClass = header.tagClass,
            tag = header.tag,
            constructed = header.constructed,

	}

	if isTruncated {
		listObjectsInfo.IsTruncated = true
		listObjectsInfo.NextContinuationToken = nextToken
	}

	return listObjectsInfo, nil
}

// getFilesFromZIPObject reads a partial stream of a zip file to build the zipindex.Files index
func getFilesListFromZIPObject(ctx context.Context, objectAPI ObjectLayer, bucket, object string, opts ObjectOptions) (zipindex.Files, ObjectInfo, error) {