1:OS REVIEW:
1 import sys,os 2 3 # print(sys.argv) #[a.py,post] can judge post or get 4 # li = sys.argv 5 # 6 # if li[1] == 'post': 7 # print('post') 8 # elif li[1] == 'down': 9 # print('1111') 10 11 #the result: 12 # E:Python_Projects>cd day27 13 # 14 # E:Python_ProjectsDay27>python os_review post 15 # python: can't open file 'os_review': [Errno 2] No such file or directory 16 # 17 # E:Python_ProjectsDay27>python os_review.py post 18 # post 19 # 20 # E:Python_ProjectsDay27>python os_review.py down 21 # 1111 22 23 # print(sys.path) 24 # for i in sys.path: 25 # print(i) 26 # print(sys.version) 27 ################################################## 28 # print(os.getcwd()) 29 # os.chdir(r'E:Python_ProjectsDay27') 30 # os.makedirs('dir1dir2dir3') 31 # os.removedirs('dir1dir2dir3') 32 # print(os.listdir(os.getcwd())) 33 # print(os.stat('os_review.py').st_size) #after the '.' include many functions 34 # os.rename('dir1dir2dir3',r'dir1dir2aaa') 35 # os.system('dir') 36 # print(os.environ) 37 # print(__file__) #get the current path's filename 38 # print(os.path.abspath(__file__)) 39 # print(os.path.split(os.path.abspath(__file__))) 40 #('E:\Python_Projects\Day27', 'os_review.py') 41 # print(os.path.dirname(os.path.dirname(os.path.abspath(__file__)))) 42 # print(os.path.join(r'd:\','www','baidu','a.py')) 43 print(os.path.join(os.path.dirname(os.path.abspath(__file__)),'dir1','dir2','123.txt'))
2:REFLECTION:
1 #>>>>>>>>>>>>>>>>>>>>reflection of files: 2 #test.py: 3 # def say_hi(): 4 # print('hello') 5 6 # import test as obj 7 # print(obj) 8 # print(hasattr(obj,'say_hi')) 9 # print(hasattr(obj,'say_hiiiiiiiii')) 10 # 11 # if hasattr(obj,'say_hi'): 12 # func=getattr(obj,'say_hi') 13 # func() 14 # else: 15 # print('other logical') 16 17 #>>>>>>>>>>>>>>>>>>>>judge the content in current file: 18 x=111 19 y=222 20 import sys 21 obj1 = sys.modules[__name__] 22 print(hasattr(obj1,'x'))
3:GETATTIBUTE ERROR:
1 class Foo: 2 def __init__(self, x): 3 self.x = x 4 5 def __getattr__(self, item): 6 print('executing __getattr__') 7 8 def __getattribute__(self, item): 9 print('executing __getattribute__') 10 raise AttributeError('abnormal') #go to __getattr__:avoid the collapse of the program 11 # raise TabError('xxxxxx') 12 13 f1 = Foo(10) 14 print(f1.x) #excuting __getattribute__ 15 # f1.xxxx #excuting __getattribute__
4:CHANGE THE DISPLAY OF THE OBJECT:
1 # l = list('hello') 2 # print(l) 3 # #['h', 'e', 'l', 'l', 'o'] 4 # 5 # file = open('test.txt','w') 6 # print(file) 7 # <_io.TextIOWrapper name='test.txt' mode='w' encoding='cp936'> 8 9 class Foo: 10 def __init__(self,name,age): 11 self.name = name 12 self.age = age 13 14 # def __str__(self): 15 # # return 'made your own diaplay of the object ' 16 # return 'the name is %s,age is %s'%(self.name,self.age) 17 18 def __repr__(self): 19 return 'the name is %s,age is %s'%(self.name,self.age) 20 21 22 # f1 = Foo() 23 f1 = Foo('alex',18) 24 print(f1) #str(f1)---->f1.__str__(),if no str will find the __repr__() 25 # <__main__.Foo object at 0x0000000002476B20> 26 # when use the __str__:the name is alex,age is 18
5:SETITEM;GETITEM AND DELITEM:
1 #>>>>>>>>>>the three method is just used in dict:use '[]' 2 3 class Foo: 4 def __getitem__(self, item): 5 print('getitem') 6 return self.__dict__[item] 7 8 def __setitem__(self, key, value): 9 print('setitem') 10 self.__dict__[key] = value 11 12 def __delitem__(self, key): 13 print('delitem') 14 self.__dict__.pop(key) 15 f1=Foo() 16 print(f1.__dict__) 17 f1['name']='zxver' 18 f1['age']='18' 19 print(f1.__dict__) 20 # {} 21 # setitem 22 # setitem 23 # {} 24 # del f1.name #did't trigure delitem 25 # print(f1.__dict__) 26 print(f1.age) #did't trigure setitem 27 del f1['name'] #trigure delitem 28 print(f1.__dict__) 29 print(f1['age'])
6:THE FORMAT OF THE TIME DISPALYING:
1 # x= '{0}{0}{0}'.format('dog') 2 # print(x) 3 4 # '{0.year} {0.mon} {0.day}' 5 # '{0.year}:{0.mon}:{0.day}' 6 # '{0.year}-{0.mon}-{0.day}' 7 format_dic ={ 8 9 'ymd':'{0.year} {0.mon} {0.day}', 10 'y:m:d':'{0.year}:{0.mon}:{0.day}', 11 'y-m-d':'{0.year}-{0.mon}-{0.day}', 12 13 } 14 class Date: 15 def __init__(self,year,mon,day): 16 self.year = year 17 self.mon = mon 18 self.day = day 19 20 def __format__(self, format_spec): 21 # print('i am execute') 22 # print('--->',format_spec) 23 if not format_spec or format_spec not in format_dic: 24 format_spec = 'ymd' 25 fm = format_dic[format_spec] 26 return fm.format(self) 27 28 d1 = Date(2020,4,22) 29 # format(d1) 30 print(format(d1,'y-m-d')) 31 print(format(d1,'')) 32 print(format(d1,'fgsfhf')) 33 # x = '{0.year} {0.mon} {0.day}'.format(d1) 34 # x = '{0.year}:{0.mon}:{0.day}'.format(d1) 35 # x = '{0.year}-{0.mon}-{0.day}'.format(d1) 36 # print(x)
7:THE INDEX OF THE FILE:
1 from dir1.dir2.a import C 2 3 c1 = C('alex') 4 print(c1.name) 5 print(c1.__module__) #dir1.dir2.a 6 print(c1.__class__) #<class 'dir1.dir2.a.C'>
8:IS INSTANCE OR IS SUBCLASS:
1 class Foo: 2 pass 3 4 f1 = Foo() 5 print(isinstance(f1,Foo)) 6 7 class Bar(Foo): 8 pass 9 # print(issubclass(Bar,Foo)) 10 b1 = Bar() 11 print(isinstance(b1,Foo)) 12 print(type(b1)) #<class '__main__.Bar'>
9:ITERABLE FILE:
1 #>>>>>>>>>>>>>>>>>>>>>>>1:provide a __next__method,use the next or report stopiteration 2 #>>>>>>>>>>>>>>>>>>>>>>>2:use the __iter__method to iterize the object 3 4 class Foo: 5 def __init__(self,n): 6 self.n = n 7 def __iter__(self): 8 return self 9 def __next__(self): 10 if self.n >= 12: 11 raise StopIteration('stop iteration') 12 self.n += 1 13 return self.n 14 15 # l=list('hello') 16 # for i in l: 17 # print(i) 18 19 f1 = Foo(10) 20 print(f1.__next__()) 21 print(f1.__next__()) 22 print(f1.__next__()) 23 # print(f1.__next__()) 24 # print(next(f1)) 25 # print(next(f1)) 26 # print(next(f1)) 27 28 # for i in f1: #f1.__iter__() == iter(f1) 29 # print(i)
10:SLOTS:# #use __slot__to replace __dict__ to save memory of objects:but use it after conider
1 # class Foo: 2 # __slots__=['name','age'] #{'name':None,'age':None} 3 # # __slots__ = 'name' 4 # 5 # f1=Foo() 6 # f1.name = 'alex' 7 # print(f1.name) 8 # # print(f1.__dict__) #>>>AttributeError: 'Foo' object has no attribute '__dict__' 9 # print(f1.__slots__) 10 # f1.age = 17 11 # print(f1.name) 12 # print(f1.age) 13 # # print(f1.gender) #wrong 14 # 15 # f2=Foo() 16 # print(f2.__slots__) 17 # f2.name='liu' 18 # f2.age=15 19 # print(f2.name) 20 # print(f2.age) 21 # #>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>doc:It can't be herited! 22 # class Foo: 23 # 'hello world!' 24 # pass 25 # class Bar(Foo): 26 # pass 27 # print(Bar.__doc__) 28 # 29 # #>>>>>>>>>>>>>>>>>>>>>>>>>>>>>module and class: 30 # #a.py: 31 # # class C: 32 # # def __init__(self,name): 33 # # self.name = 'SB' 34 # 35 # # from dir1.dir2.a import C 36 # # 37 # # c1 = C('alex') 38 # # print(c1.name) 39 # # print(c1.__module__) #dir1.dir2.a 40 # # print(c1.__class__) #<class 'dir1.dir2.a.C'> 41 # 42 # #>>>>>>>>>>>>>>>>>>>>>>>>__del__:just trigure when delete the class or when the program stop to excute will trigure it 43 # class Foo: 44 # def __init__(self,name): 45 # self.name = name 46 # def __del__(self): 47 # print('I executing') 48 # 49 # f1 = Foo('alex') 50 # # del f1.name #>>>>>>'---------->'first 51 # # del f1 #>>>>>>'I executing'first 52 # print('-------------->') ##>>>>>>'---------->'first,the same with del f1.name 53 # print('-------------->') ##>>>>>>'---------->'first,the same with del f1.name 54 55 #>>>>>>>>>>>>>>>>>>>>>>>>__call__: 56 class Foo: 57 # def __init__(self,name): 58 # self.name = name 59 def __call__(self): 60 print('I executing') 61 62 f1 = Foo() 63 f1() #Foo()'s __call__method
11:斐波那契数列：
1 class Fib: 2 def __init__(self): 3 self._a = 1 4 self._b = 1 5 6 def __iter__(self): 7 return self 8 9 def __next__(self): 10 if self._a >100: 11 raise StopIteration('stopiteration') 12 self._a,self._b = self._b,self._a + self._b 13 return self._a 14 15 f1 = Fib() 16 print(next(f1)) 17 print(next(f1)) 18 print(next(f1)) 19 print(next(f1)) 20 print('===========================') 21 for i in f1: 22 print(i)
12：THE PRIORITY:
#>>>>>>>>>>>>>>>>>>>>the priority :1,class;2,data descriptor;3,instance;
#>>>>>>>>>>>>>>>>>>>>4,nondata descripter == 5,trigure __getattr__()when can't find the attribute