compound_dict_key.py

context = {
    'database': {
        'port': 9990,
        'users': ['number2', 'dr_evil']
    },
    'admins': ['number2@virtucon.com', 'dr_evil@virtucon.com'],
    'domain.name': 'virtucon.com'
}

# Most comprehensive solution by http://stackoverflow.com/users/95810/alex-martelli
# See more about this problem at http://stackoverflow.com/questions/2841971/compound-dictionary-keys 
def getitem(context, key):
    stk = [(key.split('.'), context)]
    while stk:
      kl, ctx = stk.pop()
      if not kl: return ctx
      if kl[0].isdigit():
        ik = int(kl[0])
        try: stk.append((kl[1:], ctx[ik]))
        except LookupError: pass
      for i in range(1, len(kl) + 1):
        k = '.'.join(kl[:i])
        if k in ctx: stk.append((kl[i:], ctx[k]))
    raise KeyError(key)

if __name__ == "__main__":
    print getitem(context, 'database')
    print getitem(context, 'database.port')
    print getitem(context, 'database.users.0')
    print getitem(context, 'admins')
    print getitem(context, 'domain.name')
    try:
        getitem(context, 'database.nosuchkey')
    except KeyError, e:
        print "Error:", e