#!/usr/bin/env python
# -*- coding: utf-8 -*-

from xml.etree import ElementTree

def dump(name, obj, stream):

    def dump_dict(name, d):
        d_elem = ElementTree.Element(name, attrib={"type": "dict"})
        for k, v in d.items():
            d_elem.append(dispatch(str(k), v))
        return d_elem

    def dump_iter(name, l):
        l_elem = ElementTree.Element(name, attrib={"type": type(l).__name__})
        for v in l:
            l_elem.append(dispatch("item", v))
        return l_elem

    def dump_attr(name, a):
        a_elem = ElementTree.Element(name, attrib={"type": type(a).__name__})
        a_elem.text = "" if a == None else str(a)
        return a_elem

    def raiser(name, obj):
        msg = "{name} invalid type '{type}'".format(name=name, type=type(obj))
        raise TypeError(msg)

    def dispatch(name, obj):
        switch = {
            type(None): dump_attr,
            int: dump_attr,
            float: dump_attr,
            bool: dump_attr,
            str: dump_attr,
            unicode: dump_attr,
            list: dump_iter,
            tuple: dump_iter,
            dict: dump_dict,
        }
        func = switch.get(type(obj), raiser)
        return func(name, obj)

    root_elem = dispatch(name, obj)

    tree = ElementTree.ElementTree(root_elem)
    tree.write(stream, encoding="utf-8")

#===============================================================================
# TEST
#===============================================================================

d = {"k1": 1, "k2": 2.0, "k3": "string", "k4": [1,2,3,4]}

import StringIO

stream = StringIO.StringIO() # aca guarda el archivo

dump("d", d, stream)

print stream.getvalue()