Python基础入门之魔法方法与异常处理

class C:
	def __init__(self):
		self.x='X-man'
c=C()
c.x
'X-man'
getattr(c , 'x' , '木有这个属性')
'X-man'
getattr(c , 'y' , '木有这个属性')
'木有这个属性'

__getattr__(self,name)	

__getattribute__(self,name)

__setattr__(self,name,value)

__delattr__(self,name)

__get__(self,instance,owner)

__set__(self,instance,value)

__delete__(self,instance)

class MyDescriptor:
    def __get__(self,instance,owner):
        print("getting...",self,instance,owner)
    def __set__(self,instance,value):
        print("setting...",self,instance,value)
    def __delete__(self,instance):
        print("deleting...",self,instance)
class Test:
    x =MyDescriptor()

__len__(self)
__getitem__(self,key)
__setitem__(self,key,value)
__delitem__(self,key)
__iter__(self)
__reversed__(self)
__contains__(self,item)

for i in "FishC":
	print(i)
F
i
s
h
C

string="FishC"
it=iter(string)
next(it)
'F'
next(it)
'i'
next(it)
's'
next(it)
'h'
next(it)
'C'

my_list=["小甲鱼"]
assert len(my_list)>0
my_list.pop()
'小甲鱼'
assert len(my_list)>0
Traceback (most recent call last):
  File "<pyshell#3>", line 1, in <module>
    assert len(my_list)>0
AssertionError

my_list=[]
my_list.fishc
Traceback (most recent call last):
  File "<pyshell#1>", line 1, in <module>
    my_list.fishc
AttributeError: 'list' object has no attribute 'fishc'

my_list=[1,2,3]
my_list[3]
Traceback (most recent call last):
  File "<pyshell#3>", line 1, in <module>
    my_list[3]
IndexError: list index out of range

my_dict={"one":1,"two":2}
my_dict["three"]
Traceback (most recent call last):
  File "<pyshell#5>", line 1, in <module>
    my_dict["three"]
KeyError: 'three'

fishc
Traceback (most recent call last):
  File "<pyshell#6>", line 1, in <module>
    fishc
NameError: name 'fishc' is not defined

print"I love fishc.com"
SyntaxError: Missing parentheses in call to 'print'. Did you mean print(...)?

1+'1'
Traceback (most recent call last):
  File "<pyshell#8>", line 1, in <module>
    1+'1'
TypeError: unsupported operand type(s) for +: 'int' and 'str'

5/0
Traceback (most recent call last):
  File "<pyshell#9>", line 1, in <module>
    5/0
ZeroDivisionError: division by zero

try:
    int('abc')
    sum =1+'1'
    f =open('我是一个不存在的文档.txt')
    print(f.read())
    f.close()
except (ValueError,TypeError,OSError) as reason:
    print('出错\n错误原因是:'+str(reason)')

try:
    f =open('我是一个不存在的文档.txt')
print(f.read())
	sum=1+'1'
except:
	print('出错啦')
finally:
	f.close()

raise ZeroDivisionError5/0
Traceback (most recent call last):
  File "<pyshell#9>", line 1, in <module>
    5/0
ZeroDivisionError: division by zero

try:
    int('abc')
except ValueError as reason:
    print('出错啦:'+str(reason))
else:
    print('没有任何异常!')

try:
    with open('data.txt','w') as f:
        for each_line in f:
            print(each_line)
except OSError as reason:
    print('出错啦:'+str(reason))