Serialize my class as JSON causes "__init__() got an unexpected keyword argument 'indent'" ?

[shearichard]

Hi - I've got a straightforward class I want to serialize as JSON
(actually I want to a serialize a list of them but I believe that's
irrelevant).

I've subclassed JSONEncoder and defined my own version of the
'default' method ( based upon what I read at http://docs.python.org/library/json.html
) but when I then try to serialize the class I get the (fairly weird)
error message : "TypeError: __init__() got an unexpected keyword
argument 'indent'".

I suspect I'm doing something pretty fundamentally wrong but I don't
know what - can anyone tell me what's wrong (or alternatively tell me
how to log this as a bug ;-)

Here's my test case :

import json
class SuperPeople(object):
    pass
class People(SuperPeople, json.JSONEncoder):
    def __init__(self, name, age):
        self.__name = name
        self.__age = age
    def default(self, obj):
        if isinstance(obj, People):
            return [obj.__name, obj.__age]
        else:
            return json.JSONEncoder.default(self, obj)

def main():
    lstPeople = []
    lstPeople.append(People("Mary", 50))
    lstPeople.append(People("Joe", 40))
    lstPeople.append(People("Sue", 30))

    print json.dumps(lstPeople, cls=People)


if __name__ == "__main__":
    main()


... and this is what the stacktrace looks like  ....

Traceback (most recent call last):
  File "testJSON.py", line 24, in <module>
    main()
  File "testJSON.py", line 20, in main
    json.dumps(lstPeople, cls=People)
  File "C:\bin\installed\Python2.6\lib\json\__init__.py", line 237, in
dumps
    **kw).encode(obj)
TypeError: __init__() got an unexpected keyword argument 'indent'


... I'm running Python 2.6 on Win32.

All suggestions welcomed .

Richard.