Python中的str()会失败吗？

Question

有没有str()在Python 中抛出异常的情况？

Answer 1

是的,自定义类可能会失败:

>>> class C(object):
...     def __str__(self):
...         return 'oops: ' + oops
...
>>> c = C()
>>> str(c)
NameError: global name 'oops' is not defined

对于某些内置类,它甚至可能会失败,例如unicode:

>>> u = u'\xff'
>>> s = str(u)
UnicodeEncodeError: 'ascii' codec can't encode character u'\xff' in position 0:
ordinal not in range(128)

Answer 2

当然是:

class A(object):
    def __str__(self):
        raise Exception
a = A()
str(a)