#!/usr/bin/env python
# -*- coding:utf-8 -*-

import sys


def s1():
    print 's1'


def s2():
    print 's2'


this_module = sys.modules[__name__]

hasattr(this_module, 's1')
getattr(this_module, 's2')

导入其他模块，利用反射查找该模块是否存在某个方法


#!/usr/bin/env python
# -*- coding:utf-8 -*-

def test():
    print('from the test')

复制代码
#!/usr/bin/env python
# -*- coding:utf-8 -*-
 
"""
程序目录：
    module_test.py
    index.py
 
当前文件：
    index.py
"""

import module_test as obj

#obj.test()

print(hasattr(obj,'test'))

getattr(obj,'test')()

def fun():
    print('adfn')
import sys
a =1
t = sys.modules['__main__']
print(hasattr(t,'Foo'))
f2 = getattr(t,'ab','请求不存在')
if callable(f2):
    f2()
else:
    print(f2)

#_*_coding:utf-8_*_

format_dict={
    'nat':'{obj.name}-{obj.addr}-{obj.type}',#学校名-学校地址-学校类型
    'tna':'{obj.type}:{obj.name}:{obj.addr}',#学校类型:学校名:学校地址
    'tan':'{obj.type}/{obj.addr}/{obj.name}',#学校类型/学校地址/学校名
}
class School:
    def __init__(self,name,addr,type):
        self.name=name
        self.addr=addr
        self.type=type

    def __repr__(self):
        return 'School(%s,%s)' %(self.name,self.addr)
    def __str__(self):
        return '(%s,%s)' %(self.name,self.addr)

    def __format__(self, format_spec):
        # if format_spec
        if not format_spec or format_spec not in format_dict:
            format_spec='nat'
        fmt=format_dict[format_spec]
        return fmt.format(obj=self)

s1=School('oldboy1','北京','私立')
print('from repr: ',repr(s1))
print('from str: ',str(s1))
print(s1)

'''
str函数或者print函数--->obj.__str__()
repr或者交互式解释器--->obj.__repr__()
如果__str__没有被定义,那么就会使用__repr__来代替输出
注意:这俩方法的返回值必须是字符串,否则抛出异常
'''
print(format(s1,'nat'))
print(format(s1,'tna'))
print(format(s1,'tan'))
print(format(s1,'asfdasdffd'))
复制代码

复制代码
class B:

     def __str__(self):
         return 'str : class B'

     def __repr__(self):
         return 'repr : class B'


b=B()
print('%s'%b)
print('%r'%b)
复制代码

class A:
    a = 1
    def __init__(self,name,age,high):
        self.name = name
        self.age = age
        self.high = high
    # def __str__(self):
    #     return '被字符串的对象'
    def __repr__(self):
        return '%s'%self.name
    # def __format__(self, format_spec):
    #     return  format_spec.format(self.name,self.age,self.high)
a = A('alex',19,'175cm')
b = A('egon',19,'175cm')
print('%r'%b)
# print(str(b))
print(format(a))                        #当没有自定义%s fromate 时候他们都会向%r去找返回值
print('{a.name}-{a.age}'.format(a = a))
# egon
# alex
# alex-19      

class Foo:
    def __init__(self,name):
        self.name=name

    def __getitem__(self, item):
        print(self.__dict__[item])

    def __setitem__(self, key, value):
        self.__dict__[key]=value
    def __delitem__(self, key):
        print('del obj[key]时,我执行')
        self.__dict__.pop(key)
    def __delattr__(self, item):
        print('del obj.key时,我执行')
        self.__dict__.pop(item)

f1=Foo('sb')
f1['age']=18
f1['age1']=19
del f1.age1
del f1['age']
f1['name']='alex'
print(f1.__dict__)

__getatr__和getattr之间没有联系

class B:
    def _isinstan(self):
        pass
class A(B):
    _isinstan = None
    def __init__(self,name,age):
        self.x = 1
        self.name = name
        self.age = age
方1
    def __new__(cls, *args, **kw):
        if not cls._isinstan:
            cls.isinstan = object.__new__(cls)
        return cls.isinstan
方2
class Singleton:
    def __new__(cls, *args, **kw):
        if not hasattr(cls, '_instance'):
            cls._instance = object.__new__(cls)
        return cls._instance
a = Singleton('alex',15)

class Foo:

    def __init__(self):
        pass
    
    def __call__(self, *args, **kwargs):

        print('__call__')


obj = Foo() # 执行 __init__
obj()       # 执行 __call__

class A:
    def __init__(self):
        self.a = 1
        self.b = 2

    def __len__(self):
        return len(self.__dict__)
a = A()
print(len(a))

class A:
    def __init__(self):
        self.a = 1
        self.b = 2

    def __hash__(self):
        return hash(str(self.a)+str(self.b))
a = A()
print(hash(a))