python 回调函数

class Chainer(object):

    def __init__(self,methods,callback=None):
        self._methods=methods
        self._callback=callback
def abc(a,b):
        return a + b
a=Chainer('abc',callback=abc(3,4))
print a._methods
print a._callback
print type(a._callback)
print str(a._callback)

C:\Python27\python.exe C:/Users/TLCB/PycharmProjects/untitled/mycompany/ccc/a19.py
abc
7
<type 'int'>
7