„Kontextmanager“ (Englisch „Context Manager“) sind bestimmte Python-Objekte, die Sie in einer `with`-Anweisung verwenden können.

Beispielsweise können Sie <a href="https://docs.python.org/3/tutorial/inputoutput.html#reading-and-writing-files" class="external-link" target="_blank">`with` verwenden, um eine Datei auszulesen</a>:

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

That's why in this example we have to declare it in the `response_model` parameter.

...but continue reading below to see how to overcome that.

## Return Type and Data Filtering

しかし例外ハンドラで処理されない例外を発生させた場合は、依存関係の終了コードで処理されます。

///

## コンテキストマネージャ

### 「コンテキストマネージャ」とは

「コンテキストマネージャ」とは、`with`文の中で使用できるPythonオブジェクトのことです。

例えば、<a href="https://docs.python.org/3/tutorial/inputoutput.html#reading-and-writing-files" class="external-link" target="_blank">ファイルを読み込むには`with`を使用することができます</a>:

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

	}
}

var s2DecPool = sync.Pool{New: func() interface{} {
	// Default alloc block for network transfer.
	return s2.NewReader(nil, s2.ReaderAllocBlock(16<<10))
}}

// metacacheReader allows reading a cache stream.
type metacacheReader struct {
	mr      *msgp.Reader
	current metaCacheEntry
	err     error // stateful error
	closer  func()
	creator func() error
}

    stream.defaultReadObject();
    Comparator<Object> valueComparator = (Comparator<Object>) stream.readObject();
    int keyCount = stream.readInt();
    if (keyCount < 0) {
      throw new InvalidObjectException("Invalid key count " + keyCount);
    }
    ImmutableMap.Builder<Object, ImmutableSet<Object>> builder = ImmutableMap.builder();
    int tmpSize = 0;

    return new Splitter(strategy, omitEmptyStrings, trimmer, maxItems);
  }

  /**
   * Returns a splitter that behaves equivalently to {@code this} splitter, but automatically
   * removes leading and trailing {@linkplain CharMatcher#whitespace whitespace} from each returned
   * substring; equivalent to {@code trimResults(CharMatcher.whitespace())}. For example, {@code

        collectValueFromNonCancelledFuture(index, future);
      }
    } finally {
      /*
       * "null" means: There is no need to access `futures` again during
       * `processCompleted` because we're reading each value during a call to
       * handleOneInputDone.
       */
      decrementCountAndMaybeComplete(null);
    }
  }

  /**

	// use mtime < t+1s instead of mtime <= t to check for unmodified.
	return objTime.After(givenTime.Add(1 * time.Second))
}

// canonicalizeETag returns ETag with leading and trailing double-quotes removed,
// if any present
func canonicalizeETag(etag string) string {
	return etagRegex.ReplaceAllString(etag, "$1")
}

So, you can use it with:

```Python hl_lines="6"
{!../../docs_src/path_params/tutorial004.py!}
```

/// tip

You could need the parameter to contain `/home/johndoe/myfile.txt`, with a leading slash (`/`).

In that case, the URL would be: `/files//home/johndoe/myfile.txt`, with a double slash (`//`) between `files` and `home`.

///

## Recap

### Что такое "контекстные менеджеры"

"Контекстные менеджеры" - это любые объекты Python, которые можно использовать в операторе `with`.

Например, <a href="https://docs.python.org/3/tutorial/inputoutput.html#reading-and-writing-files" class="external-link" target="_blank">можно использовать `with` для чтения файла</a>:

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