Function validate_attributes

Solutions/7_4/structure.py:42–69

Class decorator that scans a class definition for Validators and builds a _fields variable that captures their definition order.

(cls)

        validate_attributes(cls)

def validate_attributes(cls):
    '''
    Class decorator that scans a class definition for Validators
    and builds a _fields variable that captures their definition order.
    '''
    validators = []
    for name, val in vars(cls).items():
        if isinstance(val, Validator):
            validators.append(val)

        # Apply validated decorator to any callable with annotations
        elif callable(val) and val.__annotations__:
            setattr(cls, name, validated(val))

    # Collect all of the field names
    cls._fields = tuple([v.name for v in validators])

    # Collect type conversions. The lambda x:x is an identity
    # function that's used in case no expected_type is found.
    cls._types = tuple([ getattr(v, 'expected_type', lambda x: x)
                   for v in validators ])

    # Create the __init__ method
    if cls._fields:
        cls.create_init()

    
    return cls

def typed_structure(clsname, **validators):
    cls = type(clsname, (Structure,), validators)