Raise and catch a domain-specific exception.
Python: Give a validation failure its own exception type so callers can handle it narrowly.
class InvalidAge(ValueError):
pass
def validate_age(age):
if age < 0:
raise InvalidAge("Age must be nonnegative")
return age
try:
validate_age(-1)
except InvalidAge as error:
print(error)Expected output EXAMPLE
Age must be nonnegative
Details
Save as snippet.py and run python3 snippet.py. Uses the Python standard library. Give a validation failure its own exception type so callers can handle it narrowly.
Tested on Ubuntu 24.04.5 LTS · · Python 3.12.3 · python3 3.12.3-0ubuntu2.1
Test inputs, results and environment
The exact published code ran in a dedicated Linux test container with prepared inputs. Unprivileged snippet process, external networking disabled, read-only root filesystem, and a fresh temporary working directory. Fixtures and output records are isolated from the application database. Testing covers this example and its stated checks, not every input, operating system, or runtime version. The Linux container shares its host's kernel; this is not a native Windows test.
- Architecture / host kernel
- x86_64 / 6.18.54.1-microsoft-standard-WSL2
- Snippet identity / locale
- uid=65534, gid=65534 (unprivileged) / C.UTF-8
- Interpreter invocation
python3 -c <published code>- Container image ID
sha256:32dc2d998158b6554c99b73b533f423696a0f3e31e8cbea9db10b5eee9a2fadd- Code SHA-256
f289feb4c611641586050039ead8bc09153e081c682e995f946797e4734cd637- Dependencies
- python3 3.12.3-0ubuntu2.1
Test input setup
These are the prepared inputs used by the test harness. See Details above for the prerequisites and how to run this example.
# No input files required.
Observed standard output
Age must be nonnegative
Exit code: 0. Standard error: empty. Validation: Exact stdout comparison. System-dependent values above are one recorded run.