dave at boost-consulting.com
Thu Jun 15 17:44:20 CEST 2006
John Reid <johnbaronreid at netscape.net> writes:
> I'm trying to call a python function from C++. I pass the function to
> C++ as a boost::python::object. I can call functions with no arguments,
> when I try to pass a C++ created object as an argument I get the
> following error:
> Traceback (most recent call last):
> File "python/test_python.py", line 8, in ?
> d.connect_new_deal_slot_py_2( f )
> TypeError: No to_python (by-value) converter found for C++ type: class
Actually that would be namespacename::classname. It's a C++ class
name, most probably of the return type of the C++ function
implementing your connect_new_deal_slot_py_2 method. Another
possibility is that it's the name of a C++ class of which you're
passing an instance to f inside that C++ function implementing
connect_new_deal_slot_py_2. Either way, you haven't wrapped that C++
> Now the boost.python section (http://tinyurl.com/n3cpv) in the python
> wiki answers the following question:
> "Is it is possible to convert pointers to existing classes to PyObjects*
> and then be able to pass an existing instance of an object directly to
> and from python?"
> where the last paragraph says:
> "If you really want to pass pointers around, it's certainly possible to
> tell the library to build a Python object around the pointer, but then
> you need to make sure the lifetime of the C++ object being referenced by
> the pointer extends past the lifetime of all Python references to the
> object or your program will crash."
I don't see how that relates to the error message you're seeing above.
> This is what I would like to do
which? "tell the library to build a Python object around the
Ensuring the appropriate lifetime relationships is a more complicated
topic than I can explain here, though.
> but cannot find this elsewhere in the
> documentation. Can anyone let me know how to do this?
> Thanks in advance,
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