「PYTHON」- 概念术语、基础语法

x = 5
s = "geeksforgeeks"
y = [1,2,3]
print(type(x))  # class 'int'
print(type(s))  # class 'str'
print(type(y))  # class 'list'

class QueryImpl(object):
    def __or__(self, other):
        return ...

a = QueryImpl(...)
b = QueryImpl(...)
c = a & b

a = QueryImpl(...)
b = QueryImpl(...)
c = a.__or__(b)

# https://www.cnblogs.com/wanghao123/p/7921654.html
a = x if (x>y) else y

#

a, b = 10, 20

min = a if a < b else b  # 能够嵌套

min = a < b and a or b  # [expression] and [on_true] or [on_false]

min = (b, a) [a < b]
min = {True: a, False: b} [a < b]
min = (lambda: b, lambda: a)[a < b]())

print("This line will be printed.")

x = 1
if x == 1:
    # indented four spaces
    print("x is 1.")

# https://stackoverflow.com/questions/522563/accessing-the-index-in-for-loops

for idx, val in enumerate(ints):
    print(idx, val)

if __name__ = '__main__':
	print("Hello World.")

# Excess positional argument (python 2) example:
def foo(a, b, c, *args):
    print "a = %s" % (a,)
    print "b = %s" % (b,)
    print "c = %s" % (c,)
    print args

foo("testa", "testb", "testc", "excess", "another_excess")

# Excess keyword argument (python 2) example:
def foo(a, b, c, **args):
    print "a = %s" % (a,)
    print "b = %s" % (b,)
    print "c = %s" % (c,)
    print args

foo(a="testa", d="excess", c="testc", b="testb", k="another_excess")

a = testa
b = testb
c = testc
{'k': 'another_excess', 'd': 'excess'}

# A Python program to return multiple
# values from a method using tuple

# This function returns a tuple
def fun():
	str = "geeksforgeeks"
	x = 20
	return str, x; # Return tuple, we could also
                   # write (str, x)

# Driver code to test above method
str, x = fun() # Assign returned tuple
print(str)
print(x)

# 示例一：
def simpleGeneratorFun():
    yield 1
    yield 2
    yield 3

for value in simpleGeneratorFun():
    print(value) # 将顺序打印 1 2 3

# 示例二、使用如下方法，单独调用（与「示例一」类似）
gen = simpleGeneratorFun()
print(next(gen)) # 1
print(next(gen)) # 2
print(next(gen)) # 3

# 示例三、与前两种不同
# 每次调用 simpleGeneratorFun() 将返回新的 Generator 对象
print(next(simpleGeneratorFun())) # 1
print(next(simpleGeneratorFun())) # 1
print(next(simpleGeneratorFun())) # 1

def nextSquare():
	i = 1;

	# An Infinite loop to generate squares
	while True:
		yield i*i
		i += 1 # 下一次，将从这里继续执行

for num in nextSquare():
	if num > 100:
		break
	print(num)
# 将顺序输出 1 4 9 16 ...

>>> s = 'hello'
>>> getattr(s, 'replace')('l', 'y')
'heyyo'

lambda x, y: x*y                             # 函数输入是 x 和 y，输出是它们的积 x*y
lambda: None                                 # 函数没有输入参数，输出是 None
lambda *args: sum(args)                      # 输入是任意个数的参数，输出是它们的和(隐性要求是输入参数必须能够进行加法运算)
lambda **kwargs: 1                           # 输入是任意键值对参数，输出是 1

def test_function(p1, p2, p3):
    """
    test_function does blah blah blah.

    :param p1: describe about parameter p1
    :param p2: describe about parameter p2
    :param p3: describe about parameter p3
    :return: describe what it returns
    """
    pass

# 抛出异常

raise Exception('I know Python!')
raise NotImplementedError

# 捕获异常

try:
	return True
except ZeroDivisionError:
	print("division by zero!")                                                  # Handling of exception (if required)
except IOError as exc:
	print('An exception flew by!')
else:
	print("result is", result)                                                  # execute if no exception
finally:
	return False                                                                # Some code .....(always executed)

import logging

list_of_functions = [f_a,f_b,f_c]
for current_function in list_of_functions:
    try:
        current_function()
    except KnownException:
        raise
    except Exception as e:
        logging.exception(e)

try:
    with open(filepath,'rb') as f:
        con.storbinary('STOR '+ filepath, f)
    logger.info('File successfully uploaded to '+ FTPADDR)
except Exception as e: # work on python 3.x
    logger.error('Failed to upload to ftp: %s', e)