Issue 26885: Add parsing support for more types in xmlrpc

Apache XML-RPC server supports additional data types (http://ws.apache.org/xmlrpc/types.html). Proposed patch adds support of parsing some of these types: "ex:nil", "ex:i1", "ex:i2", "ex:i8", "ex:biginteger", "ex:float", "ex:bigdecimal". "nil" and "i8" without a prefix was already supported, but the support of "i8" was not documented.

The support of "ex:dateTime" can be added after resolving issue15873.

Updated documentation.

Terry, could you please look at the documentation. Is it good English or needed a correction?

Table: I believe the format is that the second column describes Pyhton objects that can be marshalled into xml for the rpc.  Sometimes a note is added about the 'return' type, which I presume is the Python object unmarshalled from xml.  From this standpoint,
":class:`int` in range from -2147483648 to 2147483647."
is correct, as well as clearer than the replacement.

I presume 'tags' are in the xml.  "Tag' is meaningless for the returned Python objects.  To me "Values get the ``<int>`` tag." is more grammatical and at least as clear.

---
+The module now supports unmarshalling additional data types used by
+Apache XML-RPC implementation for numerics and ``None``.

The following is clearer to me, although I am puzzled as the table entry for 'nil' in unchanged.

+The module now supports unmarshalling ``None`` and additional data
+types used by Apache XML-RPC implementation for numerics.

Thank you for your review Terry.

You can pass an integer in range from -2147483648 to 2147483647, and it is marshalled using the <int> tag. But when you receive tags <i1>, <i2>, etc, they are unmarshalled to integer values, and these values can be out of range from -2147483648 to 2147483647. How to document all these detail in short?

The same is with other types. xmlrpclib is more conservative with data that it sends than with data that it receives. float is marshalled using the <double> flag, but the <float> tag is unmarshalled to float too. None and datetime can be marshalled only if corresponding option is enabled, but always can be unmarshalled. Decimal can't be marshalled, but can be unmarshalled.

For now unmarshalling None is supported from the <nil> tag (this is unofficial extension). But Apache XML-RPC server produces tags with namespace: <ex:nil>, which is not supported in xmplrpclib. The patch adds the support of tags with namespaces, and therefore adds the support of unmarshalling None in Apache XML-RPC server format.

New changeset ef63e1c999bd by Serhiy Storchaka in branch 'default':
Issue #26885: xmlrpc now supports unmarshalling additional data types used
https://hg.python.org/cpython/rev/ef63e1c999bd