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import inspect
import itertools
from collections import OrderedDict
from decorator import decorator
class ValidationFailure(Exception):
def __init__(self, func, args):
self.func = func
self.__dict__.update(args)
def __repr__(self):
return u'ValidationFailure(func={func}, args={args})'.format(
func=self.func.__name__,
args=dict(
[(k, v) for (k, v) in self.__dict__.items() if k != 'func']
)
)
def __str__(self):
return repr(self)
def __unicode__(self):
return repr(self)
def __bool__(self):
return False
def __nonzero__(self):
return False
def func_args_as_dict(func, args, kwargs):
"""
Return given function's positional and key value arguments as an ordered
dictionary.
"""
_getargspec = inspect.getfullargspec
arg_names = list(
OrderedDict.fromkeys(
itertools.chain(
_getargspec(func)[0],
kwargs.keys()
)
)
)
return OrderedDict(
list(zip(arg_names, args)) +
list(kwargs.items())
)
def validator(func, *args, **kwargs):
"""
A decorator that makes given function validator.
Whenever the given function is called and returns ``False`` value
this decorator returns :class:`ValidationFailure` object.
Example::
>>> @validator
... def even(value):
... return not (value % 2)
>>> even(4)
True
>>> even(5)
ValidationFailure(func=even, args={'value': 5})
:param func: function to decorate
:param args: positional function arguments
:param kwargs: key value function arguments
"""
def wrapper(func, *args, **kwargs):
value = func(*args, **kwargs)
if not value:
return ValidationFailure(
func, func_args_as_dict(func, args, kwargs)
)
return True
return decorator(wrapper, func)
|
