raise from ...

try:
    some_dangerous_stuff()
except ValueError as e:
    ...

try:
    some_dangerous_stuff()
except ValueError:
    fallback()

Traceback (most recent call last):
  File "...", line 15, in main
    some_dangerous_stuff()
  File "...", line 10, in some_dangerous_stuff
    return int('a')
ValueError: invalid literal for int() with base 10: 'a'

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "...", line 21, in <module>
    main()
  File "...", line 17, in main
    fallback()
  File "...", line 2, in fallback
    raise RuntimeError('cannot perform action')
RuntimeError: cannot perform action

try:
    some_dangerous_stuff()
except ValueError as e:
    raise MyError(str(e))

main

func1

func2

func3

ValueError

MyError1

MyError3

MyError2

try:
    some_dangerous_stuff()
except ValueError as e:
    raise MyError(str(e))

Traceback (most recent call last):
  File "...", line 15, in main
    some_dangerous_stuff()
  File "...", line 10, in some_dangerous_stuff
    return int('a')
ValueError: invalid literal for int() with base 10: 'a'

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "...", line 21, in <module>
    main()
  File "...", line 17, in main
    raise MyError(str(e))
__main__.MyError: invalid literal for int() with base 10: 'a'

try:
    some_dangerous_stuff()
except ValueError as e:
    raise MyError('description') from e

Traceback (most recent call last):
  File "...", line 15, in main
    some_dangerous_stuff()
  File "...", line 10, in some_dangerous_stuff
    return int('a')
ValueError: invalid literal for int() with base 10: 'a'

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

Traceback (most recent call last):
  File "...", line 21, in <module>
    main()
  File "...", line 17, in main
    raise MyError('description') from e
__main__.MyError: description

def main():
    try:
        raise MyError('test')
    except MyError as e:
        print(f'context: {e.__context__}')
        print(f'cause: {e.__cause__}')

context: None
cause: None

def func1():
    return int('a')


def func2():
    try:
        func1()
    except ValueError:
        raise MyError('description')


def main():
    try:
        func2()
    except MyError as e:
        print(f'context: {e.__context__}')
        print(f'cause: {e.__cause__}')

context: invalid literal for int() with base 10: 'a'
cause: None

def func1():
    return int('a')


def func2():
    try:
        func1()
    except ValueError as ve:
        raise MyError('description') from ve


def main():
    try:
        func2()
    except MyError as e:
        print(f'context: {e.__context__}')
        print(f'cause: {e.__cause__}')

context: invalid literal for int() with base 10: 'a'
cause: invalid literal for int() with base 10: 'a'

try:
    func1()
except ValueError as ve:
    e = MyError('description')
    e.__cause__ = ve
    raise e

try:
    func1()
except ValueError as ve:
    raise MyError('description') from e

error = None
try:
    func1()
except ValueError as ve:
    error = ve

if error:
    e = MyError('description')
    raise e from error

try:
    some_dangerous_stuff()
except ValueError as e:
    some_lock.release()
    raise

try:
    some_dangerous_stuff()
finally:
    some_lock.release()

def _get_dump():
    xs = []
    for obj in gc.get_objects():
        ...
        referents = gc.get_referents(obj)
        ...
    return xs


def dump_gc_mem(signum, frame):
    dump = _get_dump()
    with pathlib.Path('mem.pickle').open('wb') as f:
        pickle.dump(dump, f)


signal.signal(signal.SIGUSR1, dump_gc_mem)

@lru_cache(maxsize=1000)
def fetch(
    self,
    data: Request,
    headers: RequestHeaders
) -> RecognizeResponse:
    ...

# arenas allocated total        = 373
# arenas reclaimed              = 0
# arenas allocated current      = 373
373 arenas * 262144 bytes/arena = 97,779,712

def _graph(self) -> AGraph:
    return self._get_state_machine()

def _graph(self) -> AGraph:
    return self._get_state_machine(use_pygraphviz=False)

raise

By persi

raise from ...

main

func1

func2

func3

ValueError

ValueError

ValueError

MyError1

MyError3

MyError2

raise

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