A Guard Clause is a validation of information used to avoid errors during execution, and enables to "fail fast".
This package provides:
- Function decorator guard clauses (All function arguments will be checked)
- General use case guard clauses
- Ability to create custom guard clauses
pip install guardian-python
from guardian import guard
@guard.none()
def buy_item(username: str, users_repository: UsersRepository, products_repository: ProductsRepository):
guard.not_alphabetic(username)
...
- numbers: zero, not_negative, not_positive, in_range, out_of_range
- strings: matches_regex, not_matches_regex, whitespace, uppercase, lowercase, not_numeric, not_alphabetic, not_alphanumeric, empty_or_whitespace
- dates: in_date_range, out_of_date_range, before, after
- general: none, contains, equals, empty (list, str, tuple...)
custom_guard.py:
from guardian import Guard
dead = Guard(name="dead", predicate=lambda v: v.HP + v.armor <= 0, description="Don't Perform if dead")
alive = Guard(name="alive", predicate=lambda v: v.HP + v.armor > 0, description="Don't Perform if alive")
main.py:
import custom_guard
@custom_guard.dead()
def shoot(enemy: Enemy):
...
@custom_guard.alive()
def revive(player: Player):
...
- property: extracts property from objects
- key: get value at key
- transformer: function to extract wanted data to guard against
@guard.none(property="name")
def login(user: User):
# if user.name is None an exception will be thrown
@guard.none(key="name")
def login(user: dict):
# if user["name"] is None an exception will be thrown
@guard.none(transformer=lambda v: v.name)
def login(user: User):
# if user.name is None an exception will be thrown
guard.matches_regex(".*el$")
def greet_user(username: str):
# username = "Daniel" will throw an exception
# username = "John" won't throw an exception
...
# Alternatively you can use:
def greet_user(username: str):
guard.matches_regex(username, ".*el$")
...
@guard.out_of_range([0, 255])
def rgb_to_hsv(r: int, g: int, b: int) -> Tuple[int, int, int]:
...
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