Differences in handling exceptions?

[hydrargyrum]

I observe differences when handling different kind of exceptions
In an interactive interpreter:

>>> import stack_data.formatting
>>> stack_data.formatting.Formatter(show_variables=True).set_hook()

A simple exception:

>>> a=1
>>> a/0
Traceback (most recent call last):
 File "<stdin>", line 1, in <module>
ZeroDivisionError: division by zero

(By the way the variable "a" is not shown)

Another kind of exception:

>>> 1+
Traceback (most recent call last):
 File "/tmp/plop-2681655/lib/python3.9/site-packages/stack_data/formatting.py", line 67, in Formatter.set_hook.<locals>.excepthook
      66 | def excepthook(_etype, evalue, _tb):
-->   67 |     self.print_exception(evalue)
               ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
_etype = <class 'SyntaxError'>
_tb = None
evalue = SyntaxError('invalid syntax', ('<stdin>', 1, 3, '1+\n'))
self = <stack_data.formatting.Formatter object at 0x7f1f5b5f1eb0>
 File "/tmp/plop-2681655/lib/python3.9/site-packages/stack_data/formatting.py", line 72, in Formatter.print_exception
      71 | def print_exception(self, e=None, *, file=None):
-->   72 |     self.print_lines(self.format_exception(e), file=file)
               ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
e = SyntaxError('invalid syntax', ('<stdin>', 1, 3, '1+\n'))
file = None
self = <stack_data.formatting.Formatter object at 0x7f1f5b5f1eb0>
 File "/tmp/plop-2681655/lib/python3.9/site-packages/stack_data/formatting.py", line 83, in Formatter.print_lines
      80 | def print_lines(self, lines, *, file=None):
      81 |     if file is None:
      82 |         file = sys.stderr
-->   83 |     for line in lines:
      84 |         print(line, file=file, end="")
file = <_io.TextIOWrapper name='<stderr>' mode='w' encoding='utf-8'>
file is None = False
line = '      84 |         print(line, file=file, end="")\n'
lines = <generator object Formatter.format_exception at 0x7f1f5b5f9040>
self = <stack_data.formatting.Formatter object at 0x7f1f5b5f1eb0>
sys.stderr = <_io.TextIOWrapper name='<stderr>' mode='w' encoding='utf-8'>
 File "/tmp/plop-2681655/lib/python3.9/site-packages/stack_data/formatting.py", line 100, in Formatter.format_exception
      96 |         yield from self.format_exception(e.__context__)
      97 |         yield traceback._context_message
      99 | yield 'Traceback (most recent call last):\n'
-->  100 | yield from self.format_stack(e.__traceback__)
     101 | yield from traceback.format_exception_only(type(e), e)
e = SyntaxError('invalid syntax', ('<stdin>', 1, 3, '1+\n'))
e is None = False
e.__suppress_context__ = False
not e.__suppress_context__ = True
self = <stack_data.formatting.Formatter object at 0x7f1f5b5f1eb0>
self.chain = True
traceback._cause_message = '\nThe above exception was the direct cause of the following exception:\n\n'
traceback._context_message = '\nDuring handling of the above exception, another exception occurred:\n\n'
type(e) = <class 'SyntaxError'>
  File "<stdin>", line 1
    1+
      ^
SyntaxError: invalid syntax

[alexmojaki]

The normal interactive interpreter doesn't give access to source code, so neither stack_data nor normal tracebacks work well.

The behaviour for a SyntaxError is surprising, I don't know why it's doing that. But it still only seems to happen in the shell which just isn't supported. Running a script like this doesn't show anything similar:

import stack_data.formatting
stack_data.formatting.Formatter(show_variables=True).set_hook()
eval("1+")

[hydrargyrum]

By the way, pressing Ctrl-C in the interactive interpreter shows the same kind of full-backtrace as with the SyntaxError.