python2.7 - python json 多态问题

Question

import json

class Students(object):
def read(self):
print r'["Tim","Bob","Alice"]'
s = Students()

print json.load(s)
结果输出来但是出现警告Traceback (most recent call last)
但是如果把print换成return就好了这是为什么呢

黄舟 · Answer

json.load(fp[, encoding[, cls[, object_hook[, parse_float[, parse_int[, parse_constant[, object_pairs_hook[, **kw]]]]]]]])¶
Deserialize fp (a .read()-supporting file-like object containing a JSON document) to a Python object using this conversion table.

The json.load method is the return value of the read method of reading a file-like object, so if you want to return a json string in the read method, printing is not possible.