d3cfe19d7e
Co-authored-by: Marco Borgeaud <89914223+marco-antognini-sonarsource@users.noreply.github.com>
84 lines
1.9 KiB
Plaintext
84 lines
1.9 KiB
Plaintext
Catching `ExceptionGroup` with ``++except*++`` will raise a `TypeError`.
|
|
|
|
== Why is this an issue?
|
|
|
|
Python 3.11 introduced ``++except*++`` and `ExceptionGroup`, making it possible to handle and raise multiple unrelated exceptions simultaneously.
|
|
|
|
In the example below, we gather multiple exceptions in an `ExceptionGroup`. This `ExceptionGroup` is then caught by a single except block:
|
|
|
|
[source,python]
|
|
----
|
|
try:
|
|
exception_group = ExceptionGroup("Files not found", [FileNotFoundError("file1.py"), FileNotFoundError("file2.py")])
|
|
|
|
raise exception_group
|
|
|
|
except ExceptionGroup as exceptions:
|
|
# Do something with all the exceptions
|
|
pass
|
|
----
|
|
|
|
To handle differently each type of exceptions present in an `ExceptionGroup`, we have to use the ``++except*++`` keyword.
|
|
|
|
[source,python]
|
|
----
|
|
try:
|
|
exception_group = ExceptionGroup("Operation errors", [ValueError("Value bigger than 100"), TypeError("Type str is not allowed")])
|
|
|
|
raise exception_group
|
|
|
|
except* ValueError as v:
|
|
# Do something with only ValueErrors
|
|
pass
|
|
|
|
except* TypeError as t:
|
|
# Do something with only TypeErrors
|
|
pass
|
|
----
|
|
|
|
While it is possible to catch the `ExceptionGroup` and `BaseExceptionGroup` types with `except`, a `TypeError` will be raised when this is done with ``++except*++``.
|
|
|
|
|
|
== How to fix it
|
|
|
|
Make sure to use `except` when catching ExceptionGroup errors.
|
|
|
|
=== Code examples
|
|
|
|
|
|
==== Noncompliant code example
|
|
|
|
[source,python,diff-id=1,diff-type=noncompliant]
|
|
----
|
|
try:
|
|
...
|
|
except* ExceptionGroup: # Noncompliant: TypeError
|
|
pass
|
|
|
|
try:
|
|
...
|
|
except* (TypeError, ExceptionGroup): # Noncompliant: TypeError
|
|
pass
|
|
----
|
|
|
|
==== Compliant solution
|
|
|
|
[source,python,diff-id=1,diff-type=compliant]
|
|
----
|
|
try:
|
|
...
|
|
except ExceptionGroup:
|
|
pass
|
|
|
|
try:
|
|
...
|
|
except (TypeError, ExceptionGroup):
|
|
pass
|
|
----
|
|
|
|
== Resources
|
|
|
|
=== Documentation
|
|
|
|
* https://peps.python.org/pep-0654/#forbidden-combinations[PEP-654] - Forbidden combinations
|