L4·OOP & Errors

🚨Exceptions

try/except/else/finally and custom errors.

tryexceptraisecustom

§ 1try / except

Catch specific exception types. Bare except: catches everything (avoid).

§ 2else / finally

else runs if no exception. finally always runs — great for cleanup.

§ 3Raising

raise ValueError('bad input'). Custom exceptions inherit from Exception.

Example

1def parse_int(s):
2    try:
3        return int(s)
4    except ValueError as e:
5        print(f"can't parse {s!r}: {e}")
6        return None
7    finally:
8        print("done")
9
10print(parse_int("42"))
11print(parse_int("oops"))

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Question 1 / 2

When does finally run?

Properties & Descriptors

Context Managers (with)