... # nothing to split on - line too long
```
-So _Black_ will eventually format it like this:
+So _Black_ will, when we implement this, format it like this:
```py3
with \
- make_context_manager(1) as cm1, \
- make_context_manager(2) as cm2, \
- make_context_manager(3) as cm3, \
- make_context_manager(4) as cm4 \
+ make_context_manager1() as cm1, \
+ make_context_manager2() as cm2, \
+ make_context_manager3() as cm3, \
+ make_context_manager4() as cm4 \
:
... # backslashes and an ugly stranded colon
```
-Although when the target version is Python 3.9 or higher, _Black_ will use parentheses
-instead since they're allowed in Python 3.9 and higher.
+Although when the target version is Python 3.9 or higher, _Black_ uses parentheses
+instead in `--preview` mode (see below) since they're allowed in Python 3.9 and higher.
+
+An alternative to consider if the backslashes in the above formatting are undesirable is
+to use {external:py:obj}`contextlib.ExitStack` to combine context managers in the
+following way:
+
+```python
+with contextlib.ExitStack() as exit_stack:
+ cm1 = exit_stack.enter_context(make_context_manager1())
+ cm2 = exit_stack.enter_context(make_context_manager2())
+ cm3 = exit_stack.enter_context(make_context_manager3())
+ cm4 = exit_stack.enter_context(make_context_manager4())
+ ...
+```
## Preview style
limit. Line continuation backslashes are converted into parenthesized strings.
Unnecessary parentheses are stripped. The stability and status of this feature is
tracked in [this issue](https://github.com/psf/black/issues/2188).
-
-### Removing trailing newlines after code block open
-
-_Black_ will remove trailing newlines after code block openings. That means that the
-following code:
-
-```python
-def my_func():
-
- print("The line above me will be deleted!")
-
- print("But the line above me won't!")
-```
-
-Will be changed to:
-
-```python
-def my_func():
- print("The line above me will be deleted!")
-
- print("But the line above me won't!")
-```
-
-This new feature will be applied to **all code blocks**: `def`, `class`, `if`, `for`,
-`while`, `with`, `case` and `match`.