If I design a function like
def f(a, b):
...
a must be in [1,2,3]. If I pass 4 to parameter a, it should raise an exception. Is there a pythonic way to limit the value range of a function argument?
Added
Please note, is there a more pythonic way to implement it? Not just a simple assert or if in.
For instance, decorator or maybe some syntactic sugar.
Yes, and also you can raise an exception if the input value is outside the desired range. For example, let's say you have a function called f that takes two integer parameters, a and b. To limit the range of a, you can use an annotation like a: int to specify that a should be an integer. Then, you can add an if statement to check if a is within the desired range. If it's not, a ValueError will be raised with a specific error message. So, if you call the function with an invalid value for a, like 4, it will raise an exception.
def f(a: int, b: int) -> int:
if a not in [1, 2, 3]:
raise ValueError("Invalid value for 'a'. Expected 1, 2, or 3.")
#rest of your functions
return result
update
In this new example, I created a decorator called value_range that you can use to limit the range of a function argument, and it's super easy to use, just apply the decorator to your function f and specify the range values you want, as you see if you pass a value outside that range, it'll raise a ValueError. It's a really neat and pythonic way to keep things in check without messy assert or if statements!
from typing import Union
def value_range(min_value: int, max_value: int):
def decorator(func):
def wrapper(a: Union[int, float], b):
if not min_value <= a <= max_value:
raise ValueError(f"Invalid value for 'a'. It should be between {min_value} and {max_value}.")
return func(a, b)
return wrapper
return decorator
@value_range(1, 3)
def f(a: int, b):
#rest of your functions
pass