python之函数用法getattr()

# -*- coding: utf-8 -*-
#python 27
#xiaodeng
#python之函数用法getattr()

#getattr()
#说明：
'''
getattr(...)
    getattr(object, name[, default]) -> value
    default:默认值

    Get a named attribute from an object; getattr(x, 'y') is equivalent to x.y.
    When a default argument is given, it is returned when the attribute doesn't
    exist; without it, an exception is raised in that case.
'''

#案例
class A():

    def __init__(self):
        self.a = 'a'

    def method(self):
        #print "method print"
        return 'xiaodeng'

a = A()
#如果有属性a则打印a，否则打印default
print getattr(a, 'a', 'default')        #a

#如果有属性b则打印b，否则打印default
print getattr(a, 'b', 'default')        #default

#如果有方法method,否则打印其地址,否则打印default
print getattr(a, 'method', 'default')   #<bound method A.method of <__main__.A instance>>

#如果有方法method,运行函数并打印None否则打印default
print getattr(a, 'test', 'default')     #default