# cached_property　緩存屬性
class cached_property(object):
    """
    Decorator that converts a method with a single self argument into a
    property cached on the instance.
    Optional ``name`` argument allows you to make cached properties of other
    methods. (e.g.  url = cached_property(get_absolute_url, name='url') )
    """
    def __init__(self, func, name=None):
        # print(f'f: {id(func)}')
        self.func = func
        self.__doc__ = getattr(func, '__doc__')
        self.name = name or func.__name__
 
    def __get__(self, instance, type=None):
        # print(f'self func: {id(self.func)}')
        # print(f'instance: {id(instance)}')
        if instance is None:
            return self
        res = instance.__dict__[self.name] = self.func(instance)
        return res
class F00():
    @cached_property
    def test(self):
        # cached_property 將會把每個實例的屬性存儲到實例的__dict__中, 實例獲取屬性時, 將會優(yōu)先從__dict__中獲取，則不會再次調(diào)用方法內(nèi)部的過程
        print(f'運行test方法內(nèi)部過程')
        return 3
    @property
    def t(self):
        print('運行t方法內(nèi)部過程')
        return 44
f = F00()
print(f.test)  # 第一次將會調(diào)用test方法內(nèi)部過程
print(f.test)  # 再次調(diào)用將直接從實例中的__dict__中直接獲取，不會再次調(diào)用方法內(nèi)部過程
print(f.t)     # 調(diào)用方法內(nèi)部過程取值
print(f.t)     # 調(diào)用方法內(nèi)部過程取值
 
# 結(jié)果輸出
# 運行test方法內(nèi)部過程
# 3
# 3
# 運行t方法內(nèi)部過程
# 44
# 運行t方法內(nèi)部過程
# 44

x = ['hello','worl','ni']
x.sort(key=len)
print(x)
# ['ni', 'worl', 'hello']

from functools import lru_cache
@lru_cache(maxsize=30)  # maxsize參數(shù)告訴lru_cache緩存最近多少個返回值
def fib(n):
    if n < 2:
        return n
    return fib(n-1) + fib(n-2)
print([fib(n) for n in range(10)])
fib.cache_clear()   # 清空緩存

from functools import partial
 
int2 = partial(int, base=8)
print(int2('123'))
# 83

from functools import partialmethod
 
class Cell:
    def __init__(self):
        self._alive = False
    @property
    def alive(self):
        return self._alive
    def set_state(self, state):
        self._alive = bool(state)
 
    set_alive = partialmethod(set_state, True)
    set_dead = partialmethod(set_state, False)
 
    print(type(partialmethod(set_state, False)))
    # <class 'functools.partialmethod'>
 
c = Cell()
c.alive
# False
 
c.set_alive()
c.alive
# True

from functools import reduce
 
l = range(1,50)
print(reduce(lambda x,y:x+y, l))
# 1225

from functools import singledispatch
@singledispatch
def fun(text):
	print('String：' + text)
 
@fun.register(int)
def _(text):
	print(text)
 
@fun.register(list)
def _(text):
	for k, v in enumerate(text):
		print(k, v)
 
@fun.register(float)
@fun.register(tuple)
def _(text):
	print('float, tuple')
fun('i am is hubo')
fun(123)
fun(['a','b','c'])
fun(1.23)
print(fun.registry)	# 所有的泛型函數(shù)
print(fun.registry[int])	# 獲取int的泛型函數(shù)
# String：i am is hubo
# 123
# 0 a
# 1 b
# 2 c
# float, tuple
# {<class 'object'>: <function fun at 0x106d10f28>, <class 'int'>: <function _ at 0x106f0b9d8>, <class 'list'>: <function _ at 0x106f0ba60>, <class 'tuple'>: <function _ at 0x106f0bb70>, <class 'float'>: <function _ at 0x106f0bb70>}
# <function _ at 0x106f0b9d8>

class Negator:
    @singledispatchmethod
    def neg(self, arg):
        raise NotImplementedError("Cannot negate a")
 
    @neg.register
    def _(self, arg: int):
        return -arg
 
    @neg.register
    def _(self, arg: bool):
        return not arg

from functools import total_ordering
 
class Person:
    # 定義相等的比較函數(shù)
    def __eq__(self,other):
        return ((self.lastname.lower(),self.firstname.lower()) == 
                (other.lastname.lower(),other.firstname.lower()))
 
    # 定義小于的比較函數(shù)
    def __lt__(self,other):
        return ((self.lastname.lower(),self.firstname.lower()) < 
                (other.lastname.lower(),other.firstname.lower()))
 
p1 = Person()
p2 = Person()
 
p1.lastname = "123"
p1.firstname = "000"
 
p2.lastname = "1231"
p2.firstname = "000"
 
print p1 < p2  # True
print p1 <= p2  # True
print p1 == p2  # False
print p1 > p2  # False
print p1 >= p2  # False

from functools import update_wrapper
def wrap2(func):
	def inner(*args):
		return func(*args)
	return update_wrapper(inner, func)
 
@wrap2
def demo():
	print('hello world')
 
print(demo.__name__)
# demo

from functools import wraps
def wrap1(func):
	@wraps(func)	# 去掉就會返回inner
	def inner(*args):
		print(func.__name__)
		return func(*args)
	return inner
 
@wrap1
def demo():
	print('hello world')
 
print(demo.__name__)
# demo