Код от днес

Днес съчинихме следното.

import unittest
import inspect

class PreconditionFailed(Exception):
    pass

def preconditions(func):
    spec = inspect.getfullargspec(func)
    expectations = [spec.annotations[arg] for arg in spec.args]

    def checked(*args):
        for (value, expectation) in zip(args, expectations):
            if not expectation(value):
                raise PreconditionFailed
        return func(*args)
    return checked

class expr:
    def __and__(self, other): return conjunction(self, other)

class conjunction(expr):
    def __init__(self, left, right):
        self.left = left
        self.right = right
    def __call__(self, arg):
        return self.left(arg) and self.right(arg)

class gt(expr):
    def __init__(self, min): self.min = min
    def __call__(self, arg): return self.min < arg

class lt(expr):
    def __init__(self, max): self.max = max
    def __call__(self, arg): return self.max > arg

class PreconditionsTest(unittest.TestCase):
    def test_calls_the_function_if_no_violations(self):
        @preconditions
        def foo(x: gt(5)):
            return 42

        self.assertEqual(42, foo(10))

    def test_checks_if_number_is_greater_than_specified(self):
        @preconditions
        def foo(x: gt(5)):
            return 42

        with self.assertRaises(PreconditionFailed):
            foo(0)

    def test_checks_if_number_is_less_than_specified(self):
        @preconditions
        def foo(x: lt(5)):
            return 42

        with self.assertRaises(PreconditionFailed):
            foo(10)

    def test_works_with_multiple_arguments(self):
        @preconditions
        def foo(x: gt(5), y: gt(10)):
            return 42

        with self.assertRaises(PreconditionFailed):
            foo(7, 7)

    def test_supports_combining_expectations(self):
        @preconditions
        def foo(x: gt(5) & lt(10)):
            return 42

        with self.assertRaises(PreconditionFailed):
            foo(20)

if __name__ == '__main__':
    unittest.main()

Пробвайте да го разширите. Споделете кода и какво сте научили и получавате точка.