Re: [Boost-users] Boost::python readonly access to nonconstant class members

21 Dec 2010

      At Tue, 21 Dec 2010 15:47:38 +0100,
Ralf Goertz wrote:
...
Hi,
is it possible to have python have readonly access to class members
that are non constant?
typedef map Links;
class DataSet {
  Links links;
}
BOOST_PYTHON_MODULE(_boosttest) {
    class_<Links>("Links")
        .def(map_indexing_suite<Links>());
class_<DataSet>("DataSet")
        .def_readonly("links",&DataSet::links);
}
Although DataSet.links is defined readonly I can change it from within
python.
If you mean that you can do

   d = DataSet()
   d.links = 1

that would be a Boost.Python bug.

If instead you mean that you can do 

   d = DataSet()
   d.links["foo"] = "bar"

that would be unsurprising (to me), intended behavior; that's just how
the Python object model works.
...
What can I do to prevent python from overwriting links?
You could always do the equivalent of

  del DataSet.__dict__["__setitem__"]

to disable it.

-- 
Dave Abrahams
BoostPro Computing
http://www.boostpro.com