Mailman 3 August 2009 - Cplusplus-sig

[Boost.Python] Request to merge some patches from trunk into 1.40 branch (was: Re: PySide has been released)
by Anderson Lizardo Aug. 23, 2009

Aug. 23, 2009

I think it was not clear in the announcement, but PySide uses Boost.Python. And for it to work properly, we need a few patches that are already in Boost SVN trunk, but in none of the release branches. Therefore, is it possible to get these patches merged into the 1.40 release branch before the final release? That would make life a lot easier for other distros to try PySide without requiring to apply patches separately. The relevant commits are listed in http://www.pyside.org/downloads/, they are: Add generic call operator support. https://svn.boost.org/trac/boost/changeset/47846 Support C++ enums which have the same value. https://svn.boost.org/trac/boost/changeset/53660 Fix unsigned integer converters. https://svn.boost.org/trac/boost/changeset/54919 Fix unsigned integer converters (update). https://svn.boost.org/trac/boost/changeset/54923 IMHO these patches fix important bugs in Boost.Python, and the first two were in trunk even before the 1.39 release, but were never merged... Thanks in advance, -- Anderson Lizardo OpenBossa Labs - INdT Manaus - Brazil

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please add python::raw_constructor
by Vaclav Smilauer Aug. 21, 2009

Aug. 21, 2009

Hi, I am successfully using raw_constructor implementation found at http://markmail.org/message/s4ksg6nfspw2wxwd (in the attachment). Wouldn't it warrant consideration for inclusion into the official boost::python, to complement raw_function? Cheers, Vaclav

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Pybindgen/pygccxml integration
by Ben Fitzpatrick Aug. 20, 2009

Aug. 20, 2009

Hi everyone, I'm just starting to check out pybindgen after the messages I've seen floating around on this mailing list, and I have a question about the pygccxml integration. I've made a pure-virtual class with a pointer return type, like so: class pure_virtual_class { virtual int get_value(int* value)=0; virtual int put_value(int value)=0; static pure_virtual_class* Create(); }; Normally I'd call add_function('get_value', retval(int), [param('int *', 'value', transfer_ownership=True)]) (I think) But since I'm scanning the headers with gccxml, I'm not sure how to tell it to transfer the ownership. Right now it's giving me a TypeConfigurationError during 'parse', which appears to be because it doesn't know how to deal with the ownership. I looked in the documentation and couldn't find anything referencing this, and none of the examples use gccxml. Any ideas? Thanks, Ben Fitzpatrick

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PySide has been released
by Renato Araujo Aug. 18, 2009

Aug. 18, 2009

Hi, The PySide team is pleased to announce the first public release of PySide: Python for Qt! PySide, its documentation, and developer resources are available at the project website, http://www.pyside.org . What is it? ----------- PySide is a project providing an LGPL'd set of Python bindings for the Qt framework. PySide already provides a full set of Qt bindings as well as automated binding generation tools. Since the whole toolset has been made available, the team expects PySide to be valuable not only to Qt software developers, but to people willing to create Python bindings to any Qt-based library, or to any C++ library in general. Although based on a different technical approach, PySide will initially be API-compatible with existing Python bindings for Qt. PySide is still a work in progress, and some work is still required to stabilize the codebase. This being said, the team believes it is already in a usable state, especially if an occasional rough edge and unpainted surface can be tolerated. Due to practical reasons, the initial development efforts have been focused on Linux, but the team hopes people to join in porting the code to other platforms and to further develop the bindings and tools. Regards and thanks for your support guys PySide team

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Documentation bug
by Daniel James Aug. 18, 2009

Aug. 18, 2009

Hi, Trac ticket 1890, 'Missing parameters in example code' looks like a pretty trivial fix, if someone can confirm that it's correct, I'll make the change if no one else can. https://svn.boost.org/trac/boost/ticket/1890 > On the page: > > http://www.boost.org/doc/libs/1_35_0/libs/python/doc/tutorial/doc/html/pyth… > > object ignored = exec("hello = file('hello.txt', 'w')\n" > > "hello.write('Hello world!')\n" > "hello.close()", main_namespace); > > should be: > > object ignored = exec("hello = file('hello.txt', 'w')\n" > > "hello.write('Hello world!')\n" > "hello.close()", main_namespace, main_namespace); thanks, Daniel

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How to correctly expose back shared_ptr-ed Python object to C++
by Nodir GULYAMOV Aug. 10, 2009

Aug. 10, 2009

Hello All, I am trying to implement plug-ins system using BOOST Python but a little stuck. I've read documentation a couple of times and have feeling that missed something pretty simple. Below simplified version what I am trying to do: // abstract Base interface class class IBasePlugins { public: virtual ~IBasePlugins() {}; virtual bool canHandle(int type) = 0; virtual void handle() = 0; }; //some C++ internal plugin (no need to expose to python) class IntrPlugin : public IBasePlugins { public: IntrPlugin() : handle_type(1) {} bool canHandle(int type) { return type == handle_type; } void handle() { std::cout << "handle() from internal plugin" << std::endl; } private: int handle_type; }; // class to manage plug-ins typedef boost::shared_ptr<IPlugins> PluginsPtrType; typedef vector<PluginsPtrType> VPluginsType; class PluginsMgr { public: static void register(PluginsPtrType plugin) { vplugins.puch_back(plugin); } static void run(int type) { VPluginsType::iterator it; for(it = vplugins.begin(); it != vplugins.end(); it++) if( (*it)->canHandle(type) ) (*it)->handle(); } private: VPluginsType vplugins; }; // export to python struct IBasePluginsWrap : public IBasePlugins { IBasePluginsWrap(PyObject* self_): self(self_) {} bool canHandle(int type) { return call_method< bool >(self, "canHandle", type); } void handle() { call_method< void >(self, "handle"); } PyObject* self; }; BOOST_PYTHON_MODULE(pyPlugins) { class_< IBasePlugins, IBasePluginsWrap, boost::noncopyable >("IBasePlugins") .def("canHandle", pure_virtual(&IBasePlugins::canHandle)) .def("handle", pure_virtual(&IBasePlugins::handle)) ; class_< PluginsMgr >("PluginsMgr") .def("registerPlugin", &PlgMgr::registerPlugin) .staticmethod("registerPlugin") .def("run", &PlgMgr::run) .staticmethod("run") ; register_ptr_to_python<PluginsPtrType>(); } Then I am using it from python as follows: from pyPlugins import * class PyTestPlugin(IBasePlugins): def __init__(self): self.handle_type = 2 def canHandle(self, type): return type == handle_type def handle(self): print "handle() from python plugin" pm = PluginsMgr() testplg = PyTestPlugin() pm.registerPlugin(testplg) And have error that C++ signature mismatch. Thank you in advance. I will really appreciate any help. Kind regards, Nodir

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[Py++] RuntimeError: `Py++` is going to write different content to the same file
by Razvan Yorik Aug. 7, 2009

Aug. 7, 2009

Hello, I have a problem wrapping the following header file using Py++. The class "Derived<T>" defines a local typedef "Helper" which has different meanings for each template parameter "T". Wrapped header: ---------- test.h ---------- #ifndef TEST_H #define TEST_H template<class T> class Base{ public: }; template<class T> class Derived: public Base<T>{ public: typedef Base<T> Helper; }; #ifdef __GCCXML__ void instantiate(){ sizeof(Base<int>); sizeof(Base<float>); sizeof(Derived<int>); sizeof(Derived<float>); } #endif #endif ---------- end of test.h ---------- This leads to the error (full output log at the end of this email): RuntimeError: `Py++` is going to write different content to the same file(split/Helper.pypp.hpp). The following is a short list of possible explanations for this behaviour: * `Py++` bug, in this case, please report it * module_builder_t contains two or more classes with the same alias * module_builder_t contains two or more classes with the same wrapper alias Please carefully review `Py++` warning messages. It should contain an additional information. I tried to rename or exclude the "Helper" class from the wrapper, but the problem is, that it is not even in mb.classes(): >print [c.name for c in mb.classes()] ['Derived<float>', 'Derived<int>', 'Base<float>', 'Base<int>'] Is there a possibility to - rename the different Helpers to "HelperInt" and "HelperFloat" in the code generator or - apply minor changes to the header only for GCCXML, but without changing the classes (they are simplified from a bigger project!) - or to exclude the Helper class? I hope someone can suggest a solution or a workaround. Thank you Razvan Code generator: ---------- generate_code.py ---------- import os from pyplusplus import module_builder from pyplusplus.decl_wrappers import call_policies from pygccxml.declarations.matchers import access_type_matcher_t from pyplusplus import function_transformers as FT files=['test.H'] mb = module_builder.module_builder_t( files=files, define_symbols=[], include_paths=[] ) mb.build_code_creator( module_name='pytest' ) mb.code_creator.user_defined_directories.append( os.path.abspath('.') ) mb.split_module("split") mb.write_module( os.path.join( os.path.abspath('.'), 'generated.cpp' ) ) ---------- end of generate_code.py ---------- ---------- complete ouput ---------- $ python generate_code.py INFO Parsing source file "test.H" ... INFO gccxml cmd: /usr/local/bin/gccxml -I"." "test.H" -fxml="/tmp/tmpM2O_z-.xml" INFO GCCXML version - 0.9( 1.128 ) WARNING: Base<float> [class] > warning W1047: There are two or more classes that use same alias("Helper"). Duplicated aliases causes few problems, but the main one is that some > of the classes will not be exposed to Python.Other classes : Base<int> [class] WARNING: Base<int> [class] > warning W1047: There are two or more classes that use same alias("Helper"). Duplicated aliases causes few problems, but the main one is that some > of the classes will not be exposed to Python.Other classes : Base<float> [class] Traceback (most recent call last): File "generate_code.py", line 20, in <module> mb.split_module("split") File "/usr/lib/python2.5/site-packages/pyplusplus/module_builder/boost_python_builder.py", line 373, in split_module , encoding=self.encoding) File "/usr/lib/python2.5/site-packages/pyplusplus/file_writers/__init__.py", line 37, in write_multiple_files mfs.write() File "/usr/lib/python2.5/site-packages/pyplusplus/file_writers/multiple_files.py", line 406, in write self.split_classes() File "/usr/lib/python2.5/site-packages/pyplusplus/file_writers/multiple_files.py", line 307, in split_classes map( self.split_class, class_creators ) File "/usr/lib/python2.5/site-packages/pyplusplus/file_writers/multiple_files.py", line 294, in split_class self.split_class_impl( class_creator ) File "/usr/lib/python2.5/site-packages/pyplusplus/file_writers/multiple_files.py", line 268, in split_class_impl , self.create_function_code( function_name ) ) ) File "/usr/lib/python2.5/site-packages/pyplusplus/file_writers/multiple_files.py", line 58, in write_file raise RuntimeError( os.linesep.join(msg) ) RuntimeError: `Py++` is going to write different content to the same file(split/Helper.pypp.hpp). The following is a short list of possible explanations for this behaviour: * `Py++` bug, in this case, please report it * module_builder_t contains two or more classes with the same alias * module_builder_t contains two or more classes with the same wrapper alias Please carefully review `Py++` warning messages. It should contain an additional information. ---------- end of output----------

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Details of Boost.Python Py_Finalize issue?
by Haoyu Bai Aug. 7, 2009

Aug. 7, 2009

Hello, As suggested by Stefan, I'm looking into the Boost.Python Py_Finalize issue. According to Boost.Python manual, the issue is: "Currently Boost.Python has several global (or function-static) objects whose existence keeps reference counts from dropping to zero until the Boost.Python shared object is unloaded. This can cause a crash because when the reference counts do go to zero, there's no interpreter. In order to make it safe to call PyFinalize() we must register an atexit routine which destroys these objects and releases all Python reference counts so that Python can clean them up while there's still an interpreter." However, until now I can't reproduce the problem. I tried to modify the exec.cpp in BPL test suite to call Py_Initialize and Py_Finalize many times in a loop ( http://pastebin.com/f77279354 ), and also tried examples provided in some report like this: http://d.hatena.ne.jp/floth/20090525/1243247990 . But neither of them can cause a crash or observable memory leak on my machine (Arch Linux with gcc 4.4, Python 2.6 and Boost 1.39). I also checked BPL source code, but can't spot out any suspicious code that may cause problems. So could anyone share your experience with this issue, provide some test case or anymore information about this issue? I will try to solve it. Thank you! -- Haoyu Bai School of Computing, National University of Singapore.

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boost::python::str and Python's str and unicode types
by Robert Smallshire Aug. 4, 2009

Aug. 4, 2009

Hello, I'm looking for some confirmation that my understanding of what boost.python is doing is correct. >From what I understand boost::python::str represents the str (PyStringObject) type in Python. Unless I'm missing something, here doesn't seem to be anything like boost::python::unicode representing the unicode type (PyUnicodeObject). Boost.Python does have a built-in conversion from std::wstring to object, but this creates a str in Python, so presumably there is some (lossy?) decoding going on here. It seems that to directly create a PyUnicodeObject from C++ I will need to do one or more of the following: 1) Directly use the Python C API to create and manipulate PyUnicodeObject. 2) Create my own subclass of boost::python::object called for example 'unicode', which would be similar to the str class provided out of the box, but would use PyUnicodeObject underneath and deal with wchar_t rather than char. Correct? Many thanks, Rob DISCLAIMER: This message contains information that may be privileged or confidential and is the property of the Roxar Group. It is intended only for the person to whom it is addressed. If you are not the intended recipient, you are not authorised to read, print, retain, copy, disseminate, distribute, or use this message or any part thereof. If you receive this message in error, please notify the sender immediately and delete all copies of this message.

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Keyed properties?
by Jakob van Santen Aug. 4, 2009

Aug. 4, 2009

Hello, I'm in the process of hiding the unnecessarily verbose parts of a C++ interface behind Python properties, and I've run in to a slight problem. We have a bunch of classes that expose private std::vectors via Get(int index) and Set(int index, value_type& val) methods. Ideally, I'd like to replace thingy.GetATWDGain(1) thingy.SetATWDGain(1, 254.5) with thingy.atwd_gain[1] thingy.atwd_gain[1] = 254.5 I know how I would solve this in pure Python (something similar to this: http://code.activestate.com/recipes/440514/), but I'm wondering if there's a clever way to do this in Boost.Python without messing around with the library itself. If anyone has done this already, I'd be curious to know how. Cheers, Jakob van Santen

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