Add solutions

CH_07_generators_and_coroutines/exercise_04/solution_01.py

@@ -0,0 +1,54 @@
+import itertools
+import functools
+import contextlib
+import datetime
+from solution_00 import generate_primes
+
+
+@contextlib.contextmanager
+def timer():
+    s = datetime.datetime.now()
+    yield
+    e = datetime.datetime.now()
+    print((e - s).total_seconds())
+
+
+# copy from
+# https://github.com/mastering-python/code_2/blob/master/CH_03_pythonic_syntax/T_04_simple_is_better_than_complex.rst
+def primes_complicate():
+    sieve = dict()
+    for num in itertools.count(2):
+        if num not in sieve:
+            yield num
+            sieve[num * num] = [num]
+        else:
+            for p in sieve[num]:
+                sieve.setdefault(p + num, []).append(p)
+            del sieve[num]
+
+
+# copy from
+# https://github.com/mastering-python/code_2/blob/master/CH_03_pythonic_syntax/T_04_simple_is_better_than_complex.rst
+def primes_complex():
+    sieve = itertools.count(2)
+    while True:
+        yield (prime := next(sieve))
+        sieve = filter(prime.__rmod__, sieve)
+
+
+def main():
+    print('complicate')
+    with timer():
+        list(itertools.islice(primes_complicate(), 10000))
+
+    print('complex filter')
+    with timer():
+        list(itertools.islice(primes_complex(), 10000))
+
+    print('solution_00, complex for')
+    with timer():
+        list(itertools.islice(generate_primes(), 10000))
+
+
+if __name__ == '__main__':
+    main()

CH_13_async_io/exercise_01/solution_01.py

@@ -0,0 +1,75 @@
+import asyncio
+
+
+class AsyncMeta(type):
+
+    def __new__(mcs, name, bases, namespace):
+        cls = type.__new__(mcs, name, bases, namespace)
+        cls._instances = []
+        origin_new = cls.__new__
+
+        def __new__(cls, *args, **kwargs):
+            ins = origin_new(cls, *args, **kwargs)
+            cls._instances.append(ins)
+            return ins
+
+        cls.__new__ = __new__
+        return cls
+
+    async def close_all(cls):
+        while cls._instances:
+            await cls._instances.pop().close()
+
+    async def __aenter__(cls):
+        return cls
+
+    async def __aexit__(cls, exc_type, exc_val, exc_tb):
+        await cls.close_all()
+
+    def __del__(cls):
+        asyncio.run(cls.close_all())
+
+
+class AsyncClass(metaclass=AsyncMeta):
+
+    def __init__(self):
+        self.name = None
+
+    async def init(self, name):
+        self.name = name
+        print(f'init {name}')
+
+    @classmethod
+    async def create(cls, name):
+        ins = cls()
+        await ins.init(name)
+        return ins
+
+    async def close(self):
+        print(f'close {self.name}')
+
+
+async def main():
+    global AsyncClass
+    print('Using close method directly')
+    egg = await AsyncClass.create('egg')
+    spam = await AsyncClass.create('spam')
+    await AsyncClass.close_all()
+
+    print()
+
+    print('Using async with')
+    async with AsyncClass:
+        egg = await AsyncClass.create('egg')
+        spam = await AsyncClass.create('spam')
+
+    print()
+
+    print('Using __del__')
+    egg = await AsyncClass.create('egg')
+    spam = await AsyncClass.create('spam')
+    # del AsyncClass
+
+
+if __name__ == '__main__':
+    asyncio.run(main())