## 上下文管理器 { #context-managers }

### 什么是“上下文管理器” { #what-are-context-managers }

“上下文管理器”是你可以在 `with` 语句中使用的任意 Python 对象。

例如，[你可以用 `with` 来读取文件](https://docs.python.org/3/tutorial/inputoutput.html#reading-and-writing-files)：

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

在底层，`open("./somefile.txt")` 会创建一个“上下文管理器”对象。

Nous pouvons ensuite tester qu'il est bien utilisé.

## Lire un fichier `.env` { #reading-a-env-file }

   * Reads all of the lines from a {@link Readable} object. The lines do not include
   * line-termination characters, but do include other leading and trailing whitespace.
   *
   * <p>Does not close the {@code Readable}. If reading files or resources you should use the {@link
   * Files#readLines} and {@link Resources#readLines} methods.
   *
   * <p>This method prioritizes convenience over performance: It reads the entire input into memory

Luego podemos probar que se está usando.

## Leer un archivo `.env` { #reading-a-env-file }

Si tienes muchas configuraciones que posiblemente cambien mucho, tal vez en diferentes entornos, podría ser útil ponerlos en un archivo y luego leerlos desde allí como si fueran variables de entorno.

            and .java files in c.g.c.collect.testModule, one that it doesn't[*]. Consequently,
            c.g.c.base.testModule transitively pulls in .java files from both modules while reading
            the module description of only the prod module. And the prod module doesn't inherit all
            the modules that the test module classes use, so we get errors.

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 { #return-type-and-data-filtering }

    editor.commit()
  }

  @Test
  fun `Windows cannot write while reading`() {
    Assumptions.assumeTrue(windows)

    set("k1", "a", "a")
    val snapshot = cache["k1"]!!
    assertThat(cache.edit("k1")).isNull()
    snapshot.close()
  }

  @Test
  fun `can read while reading`() {
    set("k1", "a", "a")
    cache["k1"]!!.use { snapshot1 ->

Los "Context Managers" son aquellos objetos de Python que puedes usar en un `with` statement.

Por ejemplo, [puedes usar `with` para leer un archivo](https://docs.python.org/3/tutorial/inputoutput.html#reading-and-writing-files):

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

Internamente, `open("./somefile.txt")` crea un objeto llamado "Context Manager".

		if s3Error != testCase.s3Error {
			if _, err := io.ReadAll(testCase.req.Body); toAPIErrorCode(ctx, err) != testCase.s3Error {
				t.Fatalf("Test %d: Unexpected S3 error: want %d - got %d (got after reading request %s)", i, testCase.s3Error, s3Error, toAPIError(ctx, err).Code)
			}
		}
	}
}

func TestCheckAdminRequestAuthType(t *testing.T) {
	ctx, cancel := context.WithCancel(t.Context())
	defer cancel()

		ContentType: mime.TypeByExtension(filepath.Ext(object)),
	}

	var rc io.ReadCloser

	if file.UncompressedSize64 > 0 {
		// There may be number of header bytes before the content.
		// Reading 64K extra. This should more than cover name and any "extra" details.
		end := min(file.Offset+int64(file.CompressedSize64)+64<<10, zipObjInfo.Size)
		rs := &HTTPRangeSpec{Start: file.Offset, End: end}