RuleCheckAllKw Usage

RuleCheckAllKw decorator allows each arg of a function match all rules specified. Each arg can have seperate rules applied.

Includes features:

RuleCheckAllKw constructor args arg_info and rules work together. arg_info is a dictionary with a key of str that matches an arg name of the function that is being decorated. arg_info value is one of the following:

  • int is an index of an item in rules

  • IRule a rule to match

  • Iterator[IRule] a list of rules to match

arg_info can be mixed.

rules is a list of rules to match. Each element is an IRule or a list of IRule.

Custom IRule

Custom IRule class that limits value to a max int value of 100.

import kwhelp.rules as rules

class RuleIntMax100(rules.IRule):
    def validate(self) -> bool:
        if self.field_value > 100:
            if self.raise_errors:
                raise ValueError(
                    f"Arg error: '{self.key}' must be equal or less than 100")
            return False
        return True

Example Usage

RuleCheckAllKw decorated function.

from kwhelp.decorator import RuleCheckAllKw
import kwhelp.rules as rules

@RuleCheckAllKw(arg_info={"speed": 0, "limit": 1, "hours": 1, "name": 2},
                rules=[rules.RuleIntPositive,
                        (rules.RuleIntPositive, RuleIntMax100),
                        rules.RuleStrNotNullEmptyWs])
def speed_msg(speed, limit, **kwargs) -> str:
    name = kwargs.get('name', 'You')
    if limit > speed:
        msg = f"Current speed is '{speed}'. {name} may go faster as the limit is '{limit}'."
    elif speed == limit:
        msg = f"Current speed is '{speed}'. {name} are at the limit."
    else:
        msg = f"Please slow down limit is '{limit}' and current speed is '{speed}'."
    if 'hours' in kwargs:
        msg = msg + f" Current driving hours is '{kwargs['hours']}'."
    return msg

>>> result = speed_msg(speed=45, limit=60)
>>> print(result)
Current speed is '45'. You may go faster as the limit is '60'.

>>> result = speed_msg(speed=45, limit=60, name="John")
>>> print(result)
Current speed is '45'. John may go faster as the limit is '60'.

>>> result = speed_msg(speed=66, limit=60, hours=3, name="John")
>>> print(result)
Please slow down limit is '60' and current speed is '66'. Current driving hours is '3'.

If any rule fails validation then a RuleError is raised.

>>> result = speed_msg(speed=-2, limit=60)
kwhelp.exceptions.RuleError: RuleError: 'speed_msg' error. Argument: 'speed' failed validation.
Rule 'RuleIntPositive' Failed validation.
Expected the following rule to match: RuleIntPositive.
RuleCheckAllKw decorator error.
Inner Error Message: ValueError: Arg error: 'speed' must be a positive int value

>>> result = speed_msg(speed=66, limit=60, name="  ")
kwhelp.exceptions.RuleError: RuleError: 'speed_msg' error. Argument: 'name' failed validation.
Rule 'RuleStrNotNullEmptyWs' Failed validation.
Expected the following rule to match: RuleStrNotNullEmptyWs.
RuleCheckAllKw decorator error.
Inner Error Message: ValueError: Arg error: 'name' must not be empty or whitespace str

speed_msg decorated with a mixed arg_info with IRule instance and index to rules.

from kwhelp.decorator import RuleCheckAllKw
import kwhelp.rules as rules

@RuleCheckAllKw(arg_info={"speed": rules.RuleIntPositive, "limit": 0,
                    "hours": 0, "name": rules.RuleStrNotNullEmptyWs},
                rules=[(rules.RuleIntPositive, RuleIntMax100)])
def speed_msg(speed, limit, **kwargs) -> str:
    name = kwargs.get('name', 'You')
    if limit > speed:
        msg = f"Current speed is '{speed}'. {name} may go faster as the limit is '{limit}'."
    elif speed == limit:
        msg = f"Current speed is '{speed}'. {name} are at the limit."
    else:
        msg = f"Please slow down limit is '{limit}' and current speed is '{speed}'."
    if 'hours' in kwargs:
        msg = msg + f" Current driving hours is '{kwargs['hours']}'."
    return msg

Included Rules