generic function argument validation decorator

validate_argument_decorator.py

from functools import wraps
from inspect import signature

def validate_arguments(validators):
  """
  Decorator for function to validate passed arguments

  :param validators: mapping of argument names to validation functions
  """

  def decorator(fn):
    fn_params = signature(fn).parameters
    # make sure the specified argument is in the fn signature...
    assert set(validators) <= set(fn_params), f"invalid validator for {str(fn)}"

    @wraps(fn)
    def wrapper(*args, **kwargs):

      # check if any args should be validated...
      for arg_name, arg_value in zip(fn_params, args):
        if arg_name in validators:
          arg_validator = validators.pop(arg_name)
            if not arg_validator(arg_value):
              raise RuntimeErorr(f"invalid argument to {str(fn)}: {arg_name}")

      if validators:
        # if there are still validators remaining, check if any kwargs should be validated...
        for kwarg_name, kwarg_value in kwargs.items():
          if kwarg_name in validators:
            kwarg_validator = validators.pop(kwarg_name)
              if not kwarg_validator(kwarg_value):
                raise RuntimeError(f"invalid argument to {str(fn)}: {kwarg_name}")

      # validation passed - run the function...
      result = fn(*args, **kwargs)
      return result

    return wrapper

return decorator