## 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。

            throw new ThemeException("Theme name is empty: " + artifact);
        }
        return themeName;
    }

    /**
     * Recursively deletes a directory and all its contents.
     * Does not throw exceptions, only logs warnings if deletion fails.
     *
     * @param dir the directory to delete
     */
    protected void closeQuietly(final Path dir) {

		return fmt.Errorf(msg, path, crossMounts)
	}
	return nil
}

// readProcMounts reads the given mountFilePath (normally /proc/mounts) and produces a hash
// of the contents.  If the out argument is not nil, this fills it with MountPoint structs.
func readProcMounts(mountFilePath string) (mountInfos, error) {
	file, err := os.Open(mountFilePath)
	if err != nil {
		return nil, err
	}

        // Access common Throwable methods to exercise paths without touching the cause
        assertNotNull(ex.toString(), "toString should be non-null");
        ex.getMessage(); // don't assert content to avoid implementation assumptions

        // Verify no interactions happened with the mocked cause during construction/access
        verifyNoInteractions(mockCause);
    }

    @Test

## Context Managers { #context-managers }

### Qué son los "Context Managers" { #what-are-context-managers }

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

        return
      }

      val body = response.body

      if (!body.isEventStream()) {
        listener.onFailure(
          this,
          IllegalStateException("Invalid content-type: ${body.contentType()}"),
          response,
        )
        return
      }

      // This is a long-lived response. Cancel full-call timeouts.
      call?.timeout()?.cancel()

        try {
            return new JarFile(file);
        } catch (final IOException e) {
            throw new IORuntimeException(e);
        }
    }

    /**
     * Returns an input stream to read the contents of the specified JAR file entry.
     *
     * @param file the JAR file (must not be {@literal null})
     * @param entry the JAR file entry (must not be {@literal null})
     * @return the input stream to read the entry

	// This bucket is used for testing getObjectInfo operations.
	err := obj.MakeBucket(context.Background(), "test-getobjectinfo", MakeBucketOptions{})
	if err != nil {
		t.Fatalf("%s : %s", instanceType, err.Error())
	}
	opts := ObjectOptions{}

   * MultimapBuilder.hashKeys().arrayListValues().build(multimap)}, which provides more control over
   * the underlying data structure.
   *
   * @param multimap the multimap whose contents are copied to this multimap
   */
  public static <K extends @Nullable Object, V extends @Nullable Object>
      ArrayListMultimap<K, V> create(Multimap<? extends K, ? extends V> multimap) {

import java.io.Serializable;
import java.util.Map;
import org.jspecify.annotations.NonNull;
import org.jspecify.annotations.Nullable;

/**
 * A {@link ClassToInstanceMap} whose contents will never change, with many other important
 * properties detailed at {@link ImmutableCollection}.
 *
 * @author Kevin Bourrillion
 * @since 2.0
 */
@Immutable(containerOf = "B")
@GwtIncompatible