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try-consider-else (TRY300)

Added in v0.0.229 · Related issues · View source

Derived from the tryceratops linter.

What it does

Checks for return statements in try blocks.

Why is this bad?

The try-except statement has an else clause for code that should run only if no exceptions were raised. Returns in try blocks may exhibit confusing or unwanted behavior, such as being overridden by control flow in except and finally blocks, or unintentionally suppressing an exception.

Example

import logging


def reciprocal(n):
    try:
        rec = 1 / n
        print(f"reciprocal of {n} is {rec}")
        return rec
    except ZeroDivisionError:
        logging.exception("Exception occurred")
        raise

Use instead:

import logging


def reciprocal(n):
    try:
        rec = 1 / n
    except ZeroDivisionError:
        logging.exception("Exception occurred")
        raise
    else:
        print(f"reciprocal of {n} is {rec}")
        return rec

References