raise — Advanced Playground

Throws an exception manually

Python Playground

from contextlib import contextmanager

@contextmanager
def must_not_fail(label):
    try:
        yield
    except Exception as e:
        raise RuntimeError(f"{label} failed") from e

try:
    with must_not_fail("data load"):
        raise ValueError("bad data")
except RuntimeError as e:
    print(f"Caught: {e}")
    print(f"Original: {e.__cause__}")

# Raise in a generator
def safe_divide_gen(pairs):
    for a, b in pairs:
        try:
            yield a / b
        except ZeroDivisionError:
            yield float("inf")

results = list(safe_divide_gen([(10, 2), (5, 0), (9, 3)]))
print(results)

Output

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Exceptions raised inside context managers and generators interact with their surrounding protocol (__exit__ and throw()).

Challenge

Try modifying the code above to explore different behaviors. Can you extend the example to handle a new use case?

View all Advanced examples for raise