Raymond Hettinger <raymond.hettin...@gmail.com> added the comment:
IIRC, there was an early decision to handle only exact types and their subclasses (plus tuples). For example, os.environ and instances of collections.ChainMap are not JSON serializable. I believe the reason was that it made encoding faster, more predictable, and more likely to match round-trip expectations. For those wanting more generality, there are at least two options. The simplest option is to coerce the input to supported type. A more complete solution is to write a subclass of JSONEncoder to pass into json.dump() as the *cls* argument (there are examples of how to do this in the docs). For the specific case of mappingproxy, there is another issue. Multiple components of a class dict are not all JSON serializable, so you have the same problem yet again with getset_descriptor objects, member objects, and various slot wrappers. ---------- assignee: -> bob.ippolito nosy: +bob.ippolito, rhettinger versions: -Python 3.4, Python 3.5, Python 3.6, Python 3.7 _______________________________________ Python tracker <rep...@bugs.python.org> <https://bugs.python.org/issue34858> _______________________________________ _______________________________________________ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
