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truck-iguana opened this issue Apr 27, 2025 · 1 comment
Open

Bpython breaks when printing large data structures #1037

truck-iguana opened this issue Apr 27, 2025 · 1 comment

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@truck-iguana
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truck-iguana commented Apr 27, 2025 •
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I'm surprised I haven't found another issue raised about this, or maybe I missed it.

This is a frequent problem for me. If I am in the bpython shell and try to print out a large data structure, the shell crashes and it is frustrating. The big selling point of entering the shell is to be interactive with the environment, which means sometimes I want to display my data.

In this specific instance, I have a nested list structure. that looks like this

[
  ["string","string","string"..],
  ["string","string","string"..],
  ...
]

When I do a bit of debugging

sum([len(y) for x in my_nested_list[:50] for y in x])

I get 36453. So this means the excerpt I'm going to "print" to my screen has 36,453 bytes of characters in it, spread across 30 nested lists.

In bpython shell, when I simply do

>>> my_nested_list[:50]

The shell crashes:

Traceback (most recent call last):
  File "/path/to/venv/bin/bpython", line 8, in <module>
    sys.exit(main())
             ~~~~^^
  File "/path/to/venv/lib64/python3.13/site-packages/bpython/curtsies.py", line 245, in main
    repl.mainloop(True, paste)
    ~~~~~~~~~~~~~^^^^^^^^^^^^^
  File "/path/to/venv/lib64/python3.13/site-packages/bpython/curtsies.py", line 178, in mainloop
    self.process_event_and_paint(e)
    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~^^^
  File "/path/to/venv/lib64/python3.13/site-packages/bpython/curtsies.py", line 149, in process_event_and_paint
    scrolled = self.window.render_to_terminal(array, cursor_pos)
  File "/path/to/venv/lib64/python3.13/site-packages/curtsies/window.py", line 491, in render_to_terminal
    self.scroll_down()
    ~~~~~~~~~~~~~~~~^^
  File "/path/to/venv/lib64/python3.13/site-packages/curtsies/window.py", line 56, in scroll_down
    with self.t.location(x=0, y=1000000):
         ~~~~~~~~~~~~~~~^^^^^^^^^^^^^^^^
  File "/usr/lib64/python3.13/contextlib.py", line 141, in __enter__
    return next(self.gen)
  File "/path/to/venv/lib64/python3.13/site-packages/blessed/terminal.py", line 594, in location
    self.stream.flush()
    ~~~~~~~~~~~~~~~~~^^
  File "/path/to/venv/lib64/python3.13/site-packages/bpython/curtsiesfrontend/repl.py", line 623, in sigwinch_handler
    cursor_dy = self.get_cursor_vertical_diff()
  File "/path/to/venv/lib64/python3.13/site-packages/bpython/curtsies.py", line 118, in get_cursor_vertical_diff
    return self.window.get_cursor_vertical_diff()
           ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^^
  File "/path/to/venv/lib64/python3.13/site-packages/curtsies/window.py", line 398, in get_cursor_vertical_diff
    cursor_dy += self._get_cursor_vertical_diff_once()
                 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^^
  File "/path/to/venv/lib64/python3.13/site-packages/curtsies/window.py", line 406, in _get_cursor_vertical_diff_once
    row, col = self.get_cursor_position()
               ~~~~~~~~~~~~~~~~~~~~~~~~^^
  File "/path/to/venv/lib64/python3.13/site-packages/curtsies/window.py", line 315, in get_cursor_position
    return self.t.get_location()
           ~~~~~~~~~~~~~~~~~~~^^
  File "/path/to/venv/lib64/python3.13/site-packages/blessed/terminal.py", line 651, in get_location
    match = self._query_response(
        self.u7 or u'\x1b[6n', self.caps['cursor_report'].re_compiled, timeout
    )
  File "/path/to/venv/lib64/python3.13/site-packages/blessed/terminal.py", line 528, in _query_response
    self.stream.flush()
    ~~~~~~~~~~~~~~~~~^^
RuntimeError: reentrant call inside <_io.BufferedWriter name='<stdout>'>
@truck-iguana
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Found another issue about this bpython/curtsies/issues/173

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