Improve the default excepthook formatting for multi-... | python/cpython

Chưa có ai nhận issue này.

Proposal:

Currently, it is possible to add notes to exceptions, see BaseException.add_note, but this feature is underutilized.

One of the reasons for that, I believe, is the poor formatting in the default excepthook:

Current Output

(single note)

$ ./python
Python 3.14.0a2+ experimental free-threading build (heads/gh-127429-dirty:cc4f57a74d0, Dec  1 2024, 07:06:51) [GCC 14.2.1 20240910] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> try:
...     raise Exception('error')
... except Exception as e:
...     e.add_note('some context')
...     raise
...
Traceback (most recent call last):
  File "<python-input-0>", line 2, in <module>
    raise Exception('error')
Exception: error
some context

(with multiple notes)

$ ./python
Python 3.14.0a2+ experimental free-threading build (heads/gh-127429-dirty:cc4f57a74d0, Dec  1 2024, 07:06:51) [GCC 14.2.1 20240910] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> try:
...     raise Exception('error')
... except Exception as e:
...     e.add_note('some context')
...     e.add_note('some context 2')
...     e.add_note('some context 3')
...     raise
...
Traceback (most recent call last):
  File "<python-input-0>", line 2, in <module>
    raise Exception('error')
Exception: error
some context
some context 2
some context 3

I think if we formatted it better, making the output easier to understand, we could start seeing better adoption of this feature.

(with multiple notes)

$ ./python
Python 3.14.0a2+ experimental free-threading build (heads/gh-127429-dirty:cc4f57a74d0, Dec  1 2024, 07:06:51) [GCC 14.2.1 20240910] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> try:
...     raise Exception('error')
... except Exception as e:
...     e.add_note('some context')
...     e.add_note('some context 2')
...     e.add_note('some context 3')
...     raise
...
Traceback (most recent call last):
  File "<python-input-0>", line 2, in <module>
    raise Exception('error')
Exception: error
├── Note: some context
├── Note: some context 2
└── Note: some context 3

In addition to this, multiline exception messages could also be improved.

Current Output

(multi-line string, with no notes)

$./python
Python 3.14.0a2+ experimental free-threading build (heads/gh-127429-dirty:cc4f57a74d0, Dec  1 2024, 07:06:51) [GCC 14.2.1 20240910] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> raise Exception('some error\n\nsome context\nsome context (cont.)\n\nsome extra context')
Traceback (most recent call last):
  File "<python-input-0>", line 1, in <module>
    raise Exception('some error\n\nsome context\nsome context (cont.)\n\nsome extra context')
Exception: some error

some context
some context (cont.)

some extra context

(multi-line string, with multi-line notes)

$ ./python
Python 3.14.0a2+ experimental free-threading build (heads/gh-127429-dirty:cc4f57a74d0, Dec  1 2024, 07:06:51) [GCC 14.2.1 20240910] on linux
>>> try:
...     raise Exception('some error\n\nsome error text\nsome error text (cont.)\n\nsome more error text')
... except Exception as e:
...     e.add_note('some context\nsome context (cont.)')
...     e.add_note('some context 2\n\nsome extra context 2')
...     e.add_note('some context 3\nsome context 3 (cont.)\n\nsome extra context 3')
...     raise
...
Traceback (most recent call last):
  File "<python-input-0>", line 2, in <module>
    raise Exception('some error\n\nsome error text\nsome error text (cont.)\n\nsome more error text')
Exception: some error

some error text
some error text (cont.)

some more error text
some context
some context (cont.)
some context 2

some extra context 2
some context 3
some context 3 (cont.)

some extra context 3

The first example IMO isn't optimal, but it's okay enough, but the second example is very confusing. We could format it something like:

$ ./python
Python 3.14.0a2+ experimental free-threading build (heads/gh-127429-dirty:cc4f57a74d0, Dec  1 2024, 07:06:51) [GCC 14.2.1 20240910] on linux
>>> try:
...     raise Exception('some error\n\nsome error text\nsome error text (cont.)\n\nsome more error text')
... except Exception as e:
...     e.add_note('some context\nsome context (cont.)')
...     e.add_note('some context 2\n\nsome extra context 2')
...     e.add_note('some context 3\nsome context 3 (cont.)\n\nsome extra context 3')
...     raise
...
Traceback (most recent call last):
  File "<python-input-0>", line 2, in <module>
    raise Exception('some error\n\nsome error text\nsome error text (cont.)\n\nsome more error text')
Exception: 
│ │ some error
│ │
│ │ some error text
│ │ some error text (cont.)
│ │
│ └ some more error text
│
├── Note:
│   │ some context
│   └ some context (cont.)
│
├── Note:
│   │ some context 2
│   │ 
│   └ some extra context 2
│
└── Note:
    │ some context 3
    │ some context 3 (cont.)
    │ 
    └ some extra context 3

Has this already been discussed elsewhere?

No response given

Links to previous discussion of this feature:

No response

Bắt đầu với các entry point mặc định của CPython cho excepthook và định dạng exception; issue không nêu tên file hay test. So sánh output hiện tại với các ví dụ note một dòng và nhiều dòng được đề xuất, và coi là hoàn tất khi đạt được định dạng dạng cây như dự kiến mà không làm mất nội dung message.

Do mô hình lập chỉ mục viết ra từ nội dung của issue.

Improve the default excepthook formatting for multi-line and exception notes

Mô tả

Proposal:

Has this already been discussed elsewhere?

Links to previous discussion of this feature:

Hướng dẫn đóng góp

Bắt đầu từ đâu

Hướng nghiên cứu

Đánh giá

Improve the default excepthook formatting for multi-line and exception notes

Mô tả

Proposal:

Has this already been discussed elsewhere?

Links to previous discussion of this feature:

Hướng dẫn đóng góp

Bắt đầu từ đâu

Hướng nghiên cứu

Đánh giá

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