Deserialize by using __new__ (rebased 73)

[ionelmc]

Closes #73. Closes #65.

[codecov]

Codecov Report

❌ Patch coverage is 98.10127% with 3 lines in your changes missing coverage. Please review.
✅ Project coverage is 96.80%. Comparing base (4116639) to head (1791c15).
⚠️ Report is 54 commits behind head on master.

Files with missing lines	Patch %	Lines
src/tblib/pickling_support.py	91.66%	1 Missing and 1 partial ⚠️
tests/test_pickle_exception.py	99.13%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master      #82      +/-   ##
==========================================
+ Coverage   89.45%   96.80%   +7.35%     
==========================================
  Files           4        9       +5     
  Lines         275      564     +289     
  Branches       46       46              
==========================================
+ Hits          246      546     +300     
+ Misses         18       14       -4     
+ Partials       11        4       -7     

Flag	Coverage Δ
py310 (macos)	93.78% <96.83%> (?)
py310 (ubuntu)	93.78% <96.83%> (?)
py310 (windows)	93.78% <96.83%> (?)
py311 (macos)	96.26% <98.10%> (?)
py311 (ubuntu)	96.26% <98.10%> (?)
py311 (windows)	96.26% <98.10%> (?)
py312 (macos)	96.26% <98.10%> (?)
py312 (ubuntu)	96.26% <98.10%> (?)
py312 (windows)	96.26% <98.10%> (?)
py313 (macos)	96.26% <98.10%> (?)
py313 (ubuntu)	96.26% <98.10%> (?)
py313 (windows)	96.26% <98.10%> (?)
py314 (macos)	96.26% <96.83%> (?)
py314 (ubuntu)	96.26% <96.83%> (?)
py314 (windows)	96.26% <96.83%> (?)
py39 (macos)	93.43% <96.83%> (?)
py39 (ubuntu)	93.43% <96.83%> (?)
py39 (windows)	93.43% <96.83%> (?)
pypy310 (macos)	91.29% <96.83%> (?)
pypy310 (ubuntu)	91.29% <96.83%> (?)
pypy310 (windows)	91.29% <96.83%> (?)
pypy311 (macos)	93.78% <96.83%> (?)
pypy311 (ubuntu)	93.78% <96.83%> (?)
pypy311 (windows)	93.78% <96.83%> (?)
pypy39 (macos)	90.95% <96.83%> (?)
pypy39 (ubuntu)	90.95% <96.83%> (?)
pypy39 (windows)	90.95% <96.83%> (?)

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[oldium]

I finally got to test this and the result is different from my patch. Compare the original exception (shortened):

Traceback (most recent call last):
  File "timeslots\vss.py", line 84, in my_open
PermissionError: [Errno 13] Permission denied: 'C:\\Users\\work\\AppData\\Local\\Google\\Chrome\\User Data\\Default\\Network\\Cookies'

The above exception was the direct cause of the following exception:

Traceback (most recent call last):
  File "timeslots\controller.py", line 290, in set_browser_thread
  ...
  File "timeslots\vss.py", line 89, in my_open
timeslots.exceptions.AdminRequiredException: This operation requires administrator privileges. Please run as administrator.

deserialized with your fix:

Traceback (most recent call last):
  File "timeslots\vss.py", line 84, in my_open
PermissionError: [WinError None] Permission denied: 'C:\\Users\\work\\AppData\\Local\\Google\\Chrome\\User Data\\Default\\Network\\Cookies' -> None

The above exception was the direct cause of the following exception:

Traceback (most recent call last):
  File "timeslots\controller.py", line 290, in set_browser_thread
  ...
  File "timeslots\vss.py", line 89, in my_open
timeslots.exceptions.AdminRequiredException: This operation requires administrator privileges. Please run as administrator.

and deserialized with my version of the fix:

Traceback (most recent call last):
  File "timeslots\vss.py", line 84, in my_open
PermissionError: [Errno 13] Permission denied: 'C:\\Users\\work\\AppData\\Local\\Google\\Chrome\\User Data\\Default\\Network\\Cookies'

The above exception was the direct cause of the following exception:

Traceback (most recent call last):
  File "timeslots\controller.py", line 290, in set_browser_thread
  ...
  File "timeslots\vss.py", line 89, in my_open
timeslots.exceptions.AdminRequiredException: This operation requires administrator privileges. Please run as administrator.

[oldium]

According to the source code it is important what is being set: https://github.com/python/cpython/blob/main/Objects/exceptions.c#L2286

[ionelmc]

Huh, what version of python is that?

[oldium]

It is 3.11.9. The difference is in the __str__ output. Here is the test case. The first one passes, the second one not.

def test_oserror():
    try:
        raise OSError(2, 'err', 3, None, 5)
    except Exception as e:
        exc = e

    str_output = str(exc)
    tblib.pickling_support.install(exc)
    exc = pickle.loads(pickle.dumps(exc))

    assert isinstance(exc, OSError)
    assert exc.errno == 2
    assert exc.strerror == 'err'
    assert exc.filename == 3
    assert exc.filename2 == 5
    assert exc.__traceback__ is not None
    assert str_output == str(exc)


def test_real_oserror():
    try:
        import os
        os.open('non-existing-file', os.O_RDONLY)
        exc = None
    except Exception as e:
        exc = e

    str_output = str(exc)
    tblib.pickling_support.install(exc)
    exc = pickle.loads(pickle.dumps(exc))

    assert isinstance(exc, OSError)
    assert exc.errno == 2
    assert str_output == str(exc)

[oldium]

I am on Windows. The issue is that the Py_None and NULL are two different values, so setting the attribute values to None does not respect the original NULL value.