How to Simulate Timeout with Custom TimeoutError in Python

import time
from typing import Callable, TypeVar

T = TypeVar("T")


class TimeoutError(Exception):
    """Raised when an operation exceeds its time limit."""

    def __init__(self, message: str = "Operation timed out"):
        self.message = message
        super().__init__(self.message)


def run_with_timeout(func: Callable[..., T], timeout_seconds: float, *args, **kwargs) -> T:
    """
    Execute a function with a timeout constraint.

    Args:
        func: The callable to execute
        timeout_seconds: Maximum number of seconds allowed
        *args, **kwargs: Arguments passed to func

    Returns:
        The result of func

    Raises:
        TimeoutError: If the function takes longer than timeout_seconds
        RuntimeError: If the function raises an exception
    """
    start_time = time.monotonic()
    result = None
    error = None

    def wrapper():
        nonlocal result, error
        try:
            result = func(*args, **kwargs)
        except Exception as exc:
            error = exc

    import threading
    thread = threading.Thread(target=wrapper, daemon=True)
    thread.start()
    thread.join(timeout_seconds)

    if thread.is_alive():
        raise TimeoutError(f"Operation exceeded {timeout_seconds} seconds")

    if error:
        raise RuntimeError(f"Function raised: {error}") from error

    return result


def slow_task(delay: float) -> str:
    """Simulate a task that takes time."""
    time.sleep(delay)
    return f"Completed after {delay} seconds"


if __name__ == "__main__":
    # Example: quick task succeeds
    print(run_with_timeout(slow_task, 3, delay=1))

    # Example: slow task triggers timeout
    try:
        run_with_timeout(slow_task, 0.5, delay=2)
    except TimeoutError as e:
        print(f"Timeout: {e.message}")