[BUG] Captured console output still results in newline being printed in Jupyter

[huzecong]

• I've checked docs and closed issues for possible solutions.
• I can't find my issue in the FAQ.

Describe the bug

When using console.capture() in Jupyter, a new line gets printed to the notebook when exiting the capture context. This is unexpected, and is also different from rich's behavior in terminal (no new lines printed).

Here's a minimal example. After running the following in a Jupyter cell, 100 new lines are printed:

import rich.console

console = rich.console.Console()
for _ in range(100):
    with console.capture() as capture:
        console.print(1)

I think the issue is within Console._check_buffer. When exiting a capture context, self._render_buffer(self._buffer[:]) returns an empty string. When not in Jupyter, we eventually call self.file.write which is no-op when the text is empty. However, in Jupyter we'd call IPython.display.display, which IIUC always results in an empty line.

rich/rich/console.py

Lines 2003 to 2066 in 26152e9

	if self._buffer_index == 0:
	if self.is_jupyter: # pragma: no cover
	from .jupyter import display
	display(self._buffer, self._render_buffer(self._buffer[:]))
	del self._buffer[:]
	else:
	if WINDOWS:
	use_legacy_windows_render = False
	if self.legacy_windows:
	fileno = get_fileno(self.file)
	if fileno is not None:
	use_legacy_windows_render = (
	fileno in _STD_STREAMS_OUTPUT
	)
	if use_legacy_windows_render:
	from rich._win32_console import LegacyWindowsTerm
	from rich._windows_renderer import legacy_windows_render
	buffer = self._buffer[:]
	if self.no_color and self._color_system:
	buffer = list(Segment.remove_color(buffer))
	legacy_windows_render(buffer, LegacyWindowsTerm(self.file))
	else:
	# Either a non-std stream on legacy Windows, or modern Windows.
	text = self._render_buffer(self._buffer[:])
	# https://bugs.python.org/issue37871
	# https://github.com/python/cpython/issues/82052
	# We need to avoid writing more than 32Kb in a single write, due to the above bug
	write = self.file.write
	# Worse case scenario, every character is 4 bytes of utf-8
	MAX_WRITE = 32 * 1024 // 4
	try:
	if len(text) <= MAX_WRITE:
	write(text)
	else:
	batch: List[str] = []
	batch_append = batch.append
	size = 0
	for line in text.splitlines(True):
	if size + len(line) > MAX_WRITE and batch:
	write("".join(batch))
	batch.clear()
	size = 0
	batch_append(line)
	size += len(line)
	if batch:
	write("".join(batch))
	batch.clear()
	except UnicodeEncodeError as error:
	error.reason = f"{error.reason}\n*** You may need to add PYTHONIOENCODING=utf-8 to your environment ***"
	raise
	else:
	text = self._render_buffer(self._buffer[:])
	try:
	self.file.write(text)
	except UnicodeEncodeError as error:
	error.reason = f"{error.reason}\n*** You may need to add PYTHONIOENCODING=utf-8 to your environment ***"
	raise
	self.file.flush()
	del self._buffer[:]

Platform

Click to expand

What platform (Win/Linux/Mac) are you running on? What terminal software are you using?

I may ask you to copy and paste the output of the following commands. It may save some time if you do it now.

If you're using Rich in a terminal:

python -m rich.diagnose
pip freeze | grep rich

If you're using Rich in a Jupyter Notebook, run the following snippet in a cell
and paste the output in your bug report.

from rich.diagnose import report
report()

---

╭────────────────────── <class 'rich.console.Console'> ──────────────────────╮
│ A high level console interface.                                            │
│                                                                            │
│ ╭────────────────────────────────────────────────────────────────────────╮ │
│ │ <console width=115 ColorSystem.TRUECOLOR>                              │ │
│ ╰────────────────────────────────────────────────────────────────────────╯ │
│                                                                            │
│     color_system = 'truecolor'                                             │
│         encoding = 'utf-8'                                                 │
│             file = <ipykernel.iostream.OutStream object at 0x7f8bf0a35090> │
│           height = 100                                                     │
│    is_alt_screen = False                                                   │
│ is_dumb_terminal = False                                                   │
│   is_interactive = False                                                   │
│       is_jupyter = True                                                    │
│      is_terminal = False                                                   │
│   legacy_windows = False                                                   │
│         no_color = False                                                   │
│          options = ConsoleOptions(                                         │
│                        size=ConsoleDimensions(width=115, height=100),      │
│                        legacy_windows=False,                               │
│                        min_width=1,                                        │
│                        max_width=115,                                      │
│                        is_terminal=False,                                  │
│                        encoding='utf-8',                                   │
│                        max_height=100,                                     │
│                        justify=None,                                       │
│                        overflow=None,                                      │
│                        no_wrap=False,                                      │
│                        highlight=None,                                     │
│                        markup=None,                                        │
│                        height=None                                         │
│                    )                                                       │
│            quiet = False                                                   │
│           record = False                                                   │
│         safe_box = True                                                    │
│             size = ConsoleDimensions(width=115, height=100)                │
│        soft_wrap = False                                                   │
│           stderr = False                                                   │
│            style = None                                                    │
│         tab_size = 8                                                       │
│            width = 115                                                     │
╰────────────────────────────────────────────────────────────────────────────╯
╭─── <class 'rich._windows.WindowsConsoleFeatures'> ────╮
│ Windows features available.                           │
│                                                       │
│ ╭───────────────────────────────────────────────────╮ │
│ │ WindowsConsoleFeatures(vt=False, truecolor=False) │ │
│ ╰───────────────────────────────────────────────────╯ │
│                                                       │
│ truecolor = False                                     │
│        vt = False                                     │
╰───────────────────────────────────────────────────────╯
╭────── Environment Variables ───────╮
│ {                                  │
│     'TERM': 'xterm-color',         │
│     'COLORTERM': None,             │
│     'CLICOLOR': '1',               │
│     'NO_COLOR': None,              │
│     'TERM_PROGRAM': 'tmux',        │
│     'COLUMNS': None,               │
│     'LINES': None,                 │
│     'JUPYTER_COLUMNS': None,       │
│     'JUPYTER_LINES': None,         │
│     'JPY_PARENT_PID': '112278',    │
│     'VSCODE_VERBOSE_LOGGING': None │
│ }                                  │
╰────────────────────────────────────╯
platform="Linux"

[github-actions]

We found the following entries in the FAQ which you may find helpful:

• How do I log a renderable?
• Strange colors in console output.

Feel free to close this issue if you found an answer in the FAQ. Otherwise, please give us a little time to review.

This is an automated reply, generated by FAQtory