#!/usr/local/bin python3
# -*- coding: utf-8 -*-

'This is a module document'

__author__ = "vincen"

from package_name.module_name import what_ever_you_wanted

......

if __name__ == "__main__":
    pass

>>> print(sys.path)
['','/Library/Developer/CommandLineTools/Library/Frameworks/Python3.framework/Versions/3.8/lib/python38.zip', '/Library/Developer/CommandLineTools/Library/Frameworks/Python3.framework/Versions/3.8/lib/python3.8', '/Library/Developer/CommandLineTools/Library/Frameworks/Python3.framework/Versions/3.8/lib/python3.8/lib-dynload', '/Users/vincen/Library/Python/3.8/lib/python/site-packages', '/Library/Developer/CommandLineTools/Library/Frameworks/Python3.framework/Versions/3.8/lib/python3.8/site-packages', '/Library/Python/3.8/site-packages']

__all__ = ["echo", "surround", "reverse"]

x = b'ABC'

>>> 17 // 3  # floor devision discards the fractional part
5
>>> 5 ** 2  # 5 squared
25

>>> a = [-1, 1, 66.25, 333, 333, 1234.5]
>>> del a[0]
>>> a
[1, 66.25, 333, 333, 1234.5]

>>> del a

>>> 'Hello, %s' % 'world'
'Hello, world'
>>> 'Hi, %s, you have $%d.' % ('Michael', 1000000)
'Hi, Michael, you have $1000000.'

>>> while True:
...     pass  # Busy-wait for keyboard interrupt (Ctrl+C)

>>> class MyEmptyClass:
...     pass		# This is commonly used for creating minimal classes

>>> def initlog(*args):
...     pass   # Remember to implement this!

>>> classmates = ['Michael', 'Bob', 'Tracy', 'Vincen']
#      索引            ±0       1       2         3
#     逆序索引          -4       -3      -2        -1

>>> L = ['Apple', 123, True]

>>> s = ['python', 'java', ['asp', 'php'], 'scheme']
>>> len(s)
4

>>> classmates = ('Michael', 'Bob', 'Tracy')

>>> t = (1,)
>>> t
(1,)

>>> d = {'Michael': 95, 'Bob': 75, 'Tracy': 85}
>>> d['Michael']
95

>>> 'Thomas' in d
False

>>> d.get('Thomas')
None
>>> d.get('Thomas', -1)
-1

>>> d.pop('Bob')
75
>>> d
{'Michael': 95, 'Tracy': 85}

>>> s = set([1, 2, 3])
>>> s
{1, 2, 3}

>>> s.add(4)
>>> s
{1, 2, 3, 4}

>>> s.remove(4)
>>> s
{1, 2, 3}

>>> s1 = set([1, 2, 3])
>>> s2 = set([2, 3, 4])
>>> s1 & s2
{2, 3}
>>> s1 | s2
{1, 2, 3, 4}

def enroll(name, gender, age=6, city='Beijing')
def add_end(L=None)

def calc(*numbers)

def person(name, age, **kw)

def person(name, age, *, city, job)

>>> person('Jack', 24, city='Beijing', job='Engineer')
Jack 24 Beijing Engineer

def person(name, age, *args, city, job)

def person(name, age, *, city='Beijing', job)

>>> args = [3, 6]
>>> range(*args)
range(3, 6)			# 即[3, 4, 5]

>>> def parrot(voltage, state='a stiff', action='voom'):
...     print("voltage = %s, state = %s, action = %s" % (voltage, state, action))
...
>>> d = {"voltage": "four million", "state": "bleedin' demised", "action": "VOOM"}
>>> parrot(**d)

>>> def make_incrementor(n):
...     return lambda x: x + n
>>> f = make_incrementor(42)
>>> f(0)
42

>>> L = ['Michael', 'Sarah', 'Tracy', 'Bob', 'Jack']
>>> L[0:5:2]		# equals with L[::2]
['Michael', 'Tracy', 'Jack']

>>> squares = []
>>> for x in range(10):
...     squares.append(x**2)
>>> squares
[0, 1, 4, 9, 16, 25, 36, 49, 64, 81]

# lambda 表达式版本
squares = list(map(lambda x: x**2, range(10)))

# 列表推导式版本
squares = [x**2 for x in range(10)]

# 另一个例子
>>> [(x, y) for x in [1,2,3] for y in [3,1,4] if x != y]
[(1, 3), (1, 4), (2, 3), (2, 1), (2, 4), (3, 1), (3, 4)]

>>> a = {x for x in 'abracadabra' if x not in 'abc'}
>>> a
{'r', 'd'}

class Student(object):
    def __init__(self, name, score):
        self.name = name
        self.score = score

    def print_score(self):
        print('%s: %s' % (self.name, self.score))

if __name__ == "__main__":
    stu = Student("vincen", "80")
    stu.print_score()

class Student(object):
    def __init__(self, name, score):
        self.__name = name
        self.__score = score

    def get_name(self):
        return self.__name
    def get_score(self):
        return self.__score

    def set_name(self, name):
        self.__name = name
    def set_score(self, score):
        self.__score = score

    def print_score(self):
        print('%s: %s' % (self.name, self.score))

if __name__ == "__main__":
    stu = Student("vincen", "80")
    stu.print_score()

>>> bart._Student__name
'Bart Simpson'

class Animal(object):
    def run(self):
        print('Animal is running...')

class Dog(Animal):
    def run(self):
        print('Dog is running...')

class Cat(Animal):
    def run(self):
        print('Cat is running...')
        
class Timer(object):
    def run(self):
        print('Start...')

def run_twice(animal):
    animal.run()
    animal.run()

class Student(object):
    __slots__ = ('name', 'age') # 用tuple 定义允许绑定的属性名称

>>> def f(x):
...     return x * x
...
>>> r = map(f, [1, 2, 3, 4, 5, 6, 7, 8, 9])
>>> list(r)
[1, 4, 9, 16, 25, 36, 49, 64, 81]

>>> from functools import reduce
>>> def fn(x, y):
...     return x * 10 + y
...
>>> reduce(fn, [1, 3, 5, 7, 9])
13579

def is_odd(n):
    return n % 2 == 1
...
list(filter(is_odd, [1, 2, 4, 5, 6, 9, 10, 15]))

import functools

def log(func):
    @functools.wraps(func)
    def wrapper(*args, **kw):
        print('call %s():' % func.__name__)
        return func(*args, **kw)
    return wrapper

@log
def now():
  	print('2019-05-31')

>>> now()
call now():
2015-3-25

now = log(now)

import functools

def log(text):
    def decorator(func):
        @functools.wraps(func)
        def wrapper(*args, **kw):
            print('%s %s():' % (text, func.__name__))
            return func(*args, **kw)
        return wrapper
    return decorator

@log('execute')
def now():
    print('2015-3-25')

>>> now()
execute now():
2015-3-25

>>> now = log('execute')(now)

>>> now.__name__
'wrapper'

>>> import functools
>>> int2 = functools.partial(int, base=2)
>>> int2('1000000')
64
>>> int2('1010101')
85

def gen_example():
    print ('before any yield')    
    yield 'first yield' 
    print ('between yields')
    yield 'second yield'
    print ('no yield anymore')

gen = gen_example()
gen.next()　　　　＃ 第一次调用next
#before any yield
#'first yield'

gen.next()　　　　＃ 第二次调用next
#between yields
#'second yield'

gen.next()　　　　＃ 第三次调用next
#no yield anymore
#Traceback (most recent call last):
  #File "<stdin>", line 1, in <module>
#StopIteration

# List comprehension
>>> L = [x * x for x in range(10)]
>>> L
[0, 1, 4, 9, 16, 25, 36, 49, 64, 81]
# Generator 写法一，注意区别只是[]变成了()
>>> g = (x * x for x in range(10))
>>> next(g)
0
>>> next(g)
1
# 没有更多的元素时，抛出 StopIteration 的错误。

# Generator 写法二
def fib(max):
    n, a, b = 0, 0, 1
    while n < max:
        yield b
        a, b = b, a + b
        n = n + 1
    return 'done'

>>> f = fib(6)
>>> f
<generator object fib at 0x104feaaa0>

def odd():
    print('step 1')
    yield 1
    print('step 2')
    yield(3)
    print('step 3')
    yield(5)

>>> o = odd()
>>> next(o)
step 1
1
>>> next(o)
step 2
3
>>> next(o)
step 3
5
>>> next(o)
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
StopIteration

>>> ord('A')
65
>>> ord('中')
20013
>>> chr(66)
'B'
>>> chr(25991)
'文'

>>> 'ABC'.encode('ascii')
b'ABC'
>>> '中文'.encode('utf-8')
b'\xe4\xb8\xad\xe6\x96\x87'

>>> b'ABC'.decode('ascii')
'ABC'
>>> b'\xe4\xb8\xad\xe6\x96\x87'.decode('utf-8')
'中文'

>>> b'\xe4\xb8\xad\xff'.decode('utf-8', errors='ignore')
'中'

>>> len('ABC')
3
>>> len('中文')
2

>>> len(b'ABC')
3
>>> len(b'\xe4\xb8\xad\xe6\x96\x87')
6
>>> len('中文'.encode('utf-8'))
6

>>> 'Hello, {0}, 成绩提升了 {1:.1f}%'.format('小明', 17.125)
'Hello, 小明, 成绩提升了 17.1%'

range(5)
   0, 1, 2, 3, 4
range(5, 10)
   5, 6, 7, 8, 9
range(0, 10, 3)
   0, 3, 6, 9

>>> for i, value in enumerate(['A', 'B', 'C']):
...     print(i, value)
0 A
1 B
2 C

>>> dir('ABC')
['__add__', '__class__',..., '__subclasshook__', 'capitalize', 'casefold',..., 'zfill']