Apply a function and check custom exceptions with decorators

Question

I want to write a function that check a condition (with custom exceptions) and if no exceptions are raised it applies a function and return the result.

# Custom exceptions
class NegativeNumber(Exception):
    pass
class BigNumber(Exception):
    pass

def add_two(number):
    return number + 2

def apply_function(number, f):
    def check_condition(number, f):
        try:
            if number < 0:
                raise NegativeNumber
            if number > 10:
                raise BigNumber
        except NegativeNumber:
            return ("Negative Number")
        except BigNumber:
            return ("Big Number")
        return (f(number))
    return check_condition(number, f)


apply_function(5, add_two)

Can be this code written better using decorators?

Answer 1

You've already done most of it. I modified your function name and the structure of your code a bit. This should be what you are looking for:

# Custom exceptions
class NegativeNumber(Exception):
    pass
class BigNumber(Exception):
    pass

def check_exceptions(f):
    def wrapped(number):
        try:
            if number < 0:
                raise NegativeNumber
            if number > 10:
                raise BigNumber
        except NegativeNumber:
            return "Negative Number"
        except BigNumber:
            return "Big Number"
        return f(number)
    return wrapped

@check_exceptions
def add_two(number):
    return number + 2

for num in (-1, 5, 15):
    print(add_two(num))

Output:

Negative Number
7
Big Number