freqtrade/freqtrade

import logging
from copy import deepcopy
from functools import wraps
from typing import Any, Callable, TypeVar, cast

from freqtrade.exceptions import StrategyError


logger = logging.getLogger(__name__)


F = TypeVar("F", bound=Callable[..., Any])


def strategy_safe_wrapper(f: F, message: str = "", default_retval=None, supress_error=False) -> F:
    """
    Wrapper around user-provided methods and functions.
    Caches all exceptions and returns either the default_retval (if it's not None) or raises
    a StrategyError exception, which then needs to be handled by the calling method.
    """

    @wraps(f)
    def wrapper(*args, **kwargs):
        try:
            if "trade" in kwargs:
                # Protect accidental modifications from within the strategy
                kwargs["trade"] = deepcopy(kwargs["trade"])
            return f(*args, **kwargs)
        except ValueError as error:
            logger.warning(f"{message}Strategy caused the following exception: {error}{f}")
            if default_retval is None and not supress_error:
                raise StrategyError(str(error)) from error
            return default_retval
        except Exception as error:
            logger.exception(f"{message}Unexpected error {error} calling {f}")
            if default_retval is None and not supress_error:
                raise StrategyError(str(error)) from error
            return default_retval

    return cast(F, wrapper)