Mailman 3 November 2006 - Cplusplus-sig

[Boost.Python] shared_ptr<const T>
by Charles Flèche Nov. 24, 2006

Nov. 24, 2006

Hello everybody ! I've googled a lot and I wasn't able to find an answer for this, I think, easy beginner question. Let's say I have a that class : /////////////////// // Classe.h /////////////////// class Classe { public: Classe(); }; /////////////////// // Classe.cpp /////////////////// Classe::Classe() { } //////////////////// I'm wrapping it inside my Boost.Python section : class_< Classe >( "Classe" ) ; register_ptr_to_python< boost::shared_ptr<Classe> >(); I'd like to register a shared_ptr<const Classe>, but I am not able to do it. When I do a register_ptr_to_python< boost::shared_ptr<const Classe> >(), I have that error in my logs : [...] .../pointer_holder.hpp:138: error: invalid conversion from `const void*' to `void*' [...] How can I register a shared_ptr<const Classe> ? Thank you a lot !! -- Charles Fleche The Mill, London

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from_python non-compiletime-constant
by Neal Becker Nov. 23, 2006

Nov. 23, 2006

I need to register a from_python conversion where the type object is not a compile constant. I'm trying to write c++ code that will accept a numpy array. AFAICT, the PyTypeObject addresses aren't known at compile time, so can't be used in lvalue_from_pytype template arguments. These pointers can be found at runtime. How do I handle this?

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Split_module and file names
by Nicolas Tessore Nov. 23, 2006

Nov. 23, 2006

Hello, I stumbled into this seemingly stupid problem, but don't know a way out. I have got pretty much everything working in my setup, except for the fact that the wrapper file is 50k lines big and cl.exe crashes after some minutes compiling it. I read the Best Practices article and started to include caching, and finally split_module into my generator. Now the creation fails because of filename length. 'vector_less_std_scope_vector_less_unsigned_short_comma__std_scope_allocator _less_unsigned_short_grate___grate__comma__std_scope_allocator_less_std _scope_vector_less_unsigned_short_comma__std_scope_allocator_less_ unsigned_short_grate___grate___grate___grate_.pypp.hpp' is a 266 characters filename, and it is one of the rather short. It's just a vector<vector<unsigned short> > > . I have a ton of more nested containers, and cannot manually alias them all. Then, I tried to make a typedef vector<vector<unsigned short> > > vector_vector_ushort; but this changed nothing for me. So it may once again be proof of my ignorance, but could you point me in the right direction? It'd be eternally grateful :) N.

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Re: [C++-sig] Creating a python class from c++
by James Healey Nov. 21, 2006

Nov. 21, 2006

> James Healey wrote: > > Can any body tell me how you create a python class > > from within c++? > > > > so in my .py file I have > > > > class MyClass: > > def f(self): > > return 'hello world' > > > > > > And from my c++ code i want to be able to do.... > > > > x = new MyClass > > x.f() > > namespace bpl = boost::python; > bpl::dict global; > bpl::exec_file("your_file.py", global, global); > // load the definition > bpl::object my_class = global["MyClass"]; > // extract the new type > bpl::object my_instance = my_class(); > // instantiate it > bpl::object retn = my_instance.attr("f")(); > // call it > std::string value = bpl::extract<std::string>(retn); > // extract return value > > HTH, > Stefan I dont seem to have the exec_file command in my current boost build, I'm using 1.33.1 which was downloaded via the boost website. Send instant messages to your online friends http://uk.messenger.yahoo.com

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[ANN]Python-Ogre bindings
by Roman Yakovenko Nov. 20, 2006

Nov. 20, 2006

Hi. I am please to announce the second release of Python-Ogre. Python-Ogre is a set of Python bindings to the next libraries: * Ogre3d * CEGUI * Newton * ODE * OIS All libraries were exposed to Python using Boost.Python and Py++. Python-Ogre home page: http://python-ogre.python-hosting.com/ Py++ home page: http://language-binding.net/pyplusplus/pyplusplus.html -- Roman Yakovenko C++ Python language binding http://www.language-binding.net/

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Wrapping a base class' method
by bernhard.maeder＠zkb.ch Nov. 20, 2006

Nov. 20, 2006

Hello all I'm trying to export some base class' methods with the derived class directly. See the following code: // ----------------------------------------------------- #include <boost/python.hpp> struct my_base_class { int const & get_base_i() const { return i_; } int i_; }; struct my_class : my_base_class { int const & get_i() const { return i_; } int i_; }; using namespace boost::python; BOOST_PYTHON_MODULE(_test) { class_<my_class>("MyClass") .add_property("i", make_function(&my_class::get_i, return_value_policy<copy_const_reference>())) .add_property("basei", make_function(&my_class::get_base_i, return_value_policy<copy_const_reference>())) ; } // ----------------------------------------------------- Now python throws the following at me: h[ 1] >>> from _test import * h[ 1] >>> MyClass().basei Traceback (most recent call last): File "<stdin>", line 1, in ? Boost.Python.ArgumentError: Python argument types in None.None(MyClass) did not match C++ signature: None(my_base_class {lvalue}) So, my question is: Am I not supposed to do this at all? The same seems to work flawlessly when returning by value instead of by reference.... Thanks for your input Bernhard ___________________________________________________________________ Disclaimer: Diese Mitteilung ist nur fuer die Empfaengerin / den Empfaenger bestimmt. Fuer den Fall, dass sie von nichtberechtigten Personen empfangen wird, bitten wir diese hoeflich, die Mitteilung an die ZKB zurueckzusenden und anschliessend die Mitteilung mit allen Anhaengen sowie allfaellige Kopien zu vernichten bzw. zu loeschen. Der Gebrauch der Information ist verboten. This message is intended only for the named recipient and may contain confidential or privileged information. If you have received it in error, please advise the sender by return e-mail and delete this message and any attachments. Any unauthorised use or dissemination of this information is strictly prohibited.

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Re: [C++-sig] [Boost.Python] imports and callbacks
by Nat Goodspeed Nov. 17, 2006

Nov. 17, 2006

> -----Original Message----- > From: c++-sig-bounces+ngoodspeed=solidworks.com(a)python.org [mailto:c++- > sig-bounces+ngoodspeed=solidworks.com(a)python.org] On Behalf Of Tanguy > Fautre > Sent: Thursday, November 16, 2006 11:49 AM > To: c++-sig(a)python.org > Subject: [C++-sig] [Boost.Python] imports and callbacks > > The interpreter however complains that math.cos is unknown (i.e. > ignoring the "import math;" at the beginning of the python code). > > If I uncomment #import math in the event_callback definition, everything > works fine. [Nat] When you invoke Python from C++, are you passing the same dict for locals and globals? Whatever you're passing for globals and locals when you evaluate the class definition, are you passing the same two dicts when you re-enter the registered handler? I had a similar issue in which I simply wanted to run a customization script. I prepopulated one dict (I think globals) and passed an empty dict for locals. My inline script code worked fine -- but when I started trying to define functions and classes in the script, the nested code stopped being able to reference my global symbols. I fixed it by passing the same dict for both.

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[Boost.Python] imports and callbacks
by Tanguy Fautre Nov. 16, 2006

Nov. 16, 2006

Hi, Here is an example Python class that will be executed by an embedded Python interpreter: import math; class Subsystem: def __init__(self) : simulation.event.register(self.event_callback) def event_callback(self) : #import math cosine = math.cos(simulation_time) new_subsystem = Subsystem() As you can see, at construction the Subsystem class registers a callback functions via the simulation.event object. The simulation.event object is a C++ object exported via Boost.Python into the main namespace. The simulation.event.register function in C++ has only one argument: a boost::python::object to copy the given callback. Lets say this boost::python::object is named Function. When I call Function(), the callback is correctly called. The interpreter however complains that math.cos is unknown (i.e. ignoring the "import math;" at the beginning of the python code). If I uncomment #import math in the event_callback definition, everything works fine. At first I thought that boost::python::object was ignoring both the local and the main namespaces used by the embedded python interpreter when event_callback was registered. But I realized later that I could still access objects in the main namespace such as the simulation.event object. Is it possible that the top "import math" only affects the local namespace, and that this local namespace is not reused when the callbacked is called through a boost::python::object ? Also, what is the performance impact of the "import math" in the callback? Putting the import inside event_callback is not very annoying, as long as it does not affect performances. Tanguy

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boost::python + epydoc
by Neal Becker Nov. 16, 2006

Nov. 16, 2006

I'm using epydoc-3.0alpha3. I know we've talked about this before, but I don't think the issue was resolved. When using epydoc with boost::python doc strings, you have to turn off signatures: docstring_options doc_options (true, false); Otherwise, it seems epydoc is confused. Is there any resolution to this issue? I'd rather not have to turn off the signatures to add my documentation.

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Using PYPP_API
by Haridev, Meghana Nov. 16, 2006

Nov. 16, 2006

Hi Folks, I'm using Py++ for the generation of boost.python wrappers. I would like to use a high level API which is built on top of Py++ to abstract away the internal details of Py++/pygccxml. What is the status of the development of the PYPP_API? Is it stable enough to be used to generate consistent/reliable code in terms of using Py++ under the hood? Are all features of Py++ supported by the API or exposed in a manner that users can still use raw Py++ if need be? Thanks! -Meghana.

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