Mailman 3 February 2005 - Cplusplus-sig

RE: Wrapper for exception translation
by Gottfried.Ganssauge＠HAUFE.DE April 4, 2006

April 4, 2006

> -----Original Message----- > From: David Abrahams [mailto:dave@boost-consulting.com] > Sent: Monday, December 13, 2004 1:04 PM > To: c++-sig(a)python.org; Gottfried Ganßauge > Subject: Re: Wrapper for exception translation > > > Gottfried Ganßauge wrote: > > Hi Dave, > > > > I digged through the class_<> implementation and I think I > know what I > > must do to implement it. Like you suggested I would add another > > argument to the class_base constructor which is used as > another base > > class for the newly created class. > > Hi Gottfried, Hi Dave, > > I don't know if you're still listening, but today I offered to > implement this patch on the C++-sig (see my other post). > Are you still interested? I am still listening but was buried deeply with work so I even had to abandon the work already invested into this. Nonetheless: Yes - I'm still interested. Cheers, Gottfried P.S.: What second Post? I got 2 Copies of this one. > > > > -- > Dave Abrahams > Boost Consulting > http://www.boost-consulting.com >

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what happened with this std::string parameter in boost.python
by Donnie Leen April 4, 2005

April 4, 2005

I made a program embedding boost.python, writting a module as following: void write( std::string s ) { // do nothing } BOOST_PYTHON_MODULE(mym) { def( "write", &write ); } I run the python code: import mym s = 'hello' mym.write(s) it runs ok, but if i run the python code as following: import mym s = int.__doc__ mym.write(s) it crashed, and it seems to crashed while boost.python try to delete the parameter s. Can someone tell me what happened to it? Thanks first. Donnie Leen

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Making copy of function derived from C++ pure virtual function
by Paul F. Kunz March 23, 2005

March 23, 2005

I have a function written in Python derived from C++. Now I want to clone this function in C++. What should I do in the copy constructor of the function wrapper? I have... FunctionWrap:: FunctionWrap ( const FunctionWrap & wrap ) : FunctionBase ( wrap ), m_self ( wrap.m_self ) { // what should be here to create a new PyObject that is copy of old one? } FunctionBase * FunctionWrap:: clone () const { return new FunctionWrap ( *this ); }

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Re: [C++-sig] Re: a working example of wrapping an instantiated c++ object
by Yao Heling March 17, 2005

March 17, 2005

Ok, I'll try to write a small tutorial for this. I'll post it here when it's ready. Thanks for your help, Joseph __________________________________ Do you Yahoo!? The all-new My Yahoo! - What will yours do? http://my.yahoo.com

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.def(str(self)) compile problems
by Simon Burton Feb. 27, 2005

Feb. 27, 2005

Hi ! I'm having trouble getting the __str__ wrapper for my C++ class to compile. Everything else i've tried works fine (methods/functions/operators), but when I include the .def( str(self) ) line the compilation fails. Any help much appreciated. I am new to python/C++, but have done a lot of python/C interfacing. details follow. Simon. blue:~/home/cpp/break$ bjam -sTOOLS=gcc lift ...found 1537 targets... ...updating 2 targets... gcc-C++-action bin/break/lift.so/gcc/debug/shared-linkable-true/lift.o /home/simon/local/boost_1_32_0/boost/python/def_visitor.hpp: In static member function `static void boost::python::def_visitor_access::visit(const V&, classT&) [with V = boost::python::def_visitor<boost::python::api::object>, classT = boost::python::class_<interval, boost::python::detail::not_specified, boost::python::detail::not_specified, boost::python::detail::not_specified>]': /home/simon/local/boost_1_32_0/boost/python/def_visitor.hpp:67: instantiated from `void boost::python::def_visitor<DerivedVisitor>::visit(classT&) const [with classT = boost::python::class_<interval, boost::python::detail::not_specified, boost::python::detail::not_specified, boost::python::detail::not_specified>, DerivedVisitor = boost::python::api::object]' /home/simon/local/boost_1_32_0/boost/python/class.hpp:225: instantiated from `boost::python::class_<T, X1, X2, X3>& boost::python::class_<T, X1, X2, X3>::def(const boost::python::def_visitor<Derived>&) [with Derived = boost::python::api::object, W = interval, X1 = boost::python::detail::not_specified, X2 = boost::python::detail::not_specified, X3 = boost::python::detail::not_specified]' lift.cpp:12: instantiated from here /home/simon/local/boost_1_32_0/boost/python/def_visitor.hpp:31: error: no matching function for call to `boost::python::api::object::visit(boost::python::class_<interval, boost::python::detail::not_specified, boost::python::detail::not_specified, boost::python::detail::not_specified>&) const' set -e "g++" -c -Wall -ftemplate-depth-255 -DBOOST_PYTHON_DYNAMIC_LIB -g -O0 -fno-inline -fPIC -I"bin/break" -I "/usr/local//include/python2.3" -I "/home/simon/local/boost_1_32_0" -o "bin/break/lift.so/gcc/debug/shared-linkable-true/lift.o" "lift.cpp" "/usr/bin/objcopy" --set-section-flags .debug_str=contents,debug "bin/break/lift.so/gcc/debug/shared-linkable-true/lift.o" ...failed gcc-C++-action bin/break/lift.so/gcc/debug/shared-linkable-true/lift.o... ...removing bin/break/lift.so/gcc/debug/shared-linkable-true/lift.o ...skipped <@break/lift.so/gcc/debug/shared-linkable-true>lift.so for lack of <@break/lift.so/gcc/debug/shared-linkable-true>lift.o... ...failed updating 1 target... ...skipped 1 target... blue:~/home/cpp/break$ blue:~/home/cpp/break$ g++ --version g++ (GCC) 3.3.2 (Mandrake Linux 10.0 3.3.2-6mdk) blue:~/home/cpp/break$ cat interval.hpp class interval { public: class division : public std::exception {}; class disorder : public std::exception {}; interval() : _lower(), _upper() {} private: double _lower; double _upper; friend double lower(const interval&); friend double upper(const interval&); }; inline double lower(const interval& x) { return x._lower; } inline double upper(const interval& x) { return x._upper; } std::ostream& operator<<(std::ostream& x, interval y) { return x << '[' << lower(y) << ',' << upper(y) << ']'; } blue:~/home/cpp/break$ cat lift.cpp #include <boost/python.hpp> #include "interval.hpp" using namespace boost::python; BOOST_PYTHON_MODULE(lift) { class_< interval >("interval", init< >()) .def( str(self) ) ; def( "lower", lower ); def( "upper", upper ); } blue:~/home/cpp/break$ cat Jamfile project-root ; import python ; extension lift : lift.cpp <template>@boost/libs/python/build/extension ; blue:~/home/cpp/break$ cat Jamrules path-global BOOST_ROOT : /home/simon/local/boost_1_32_0 ; project boost : $(BOOST_ROOT) ; blue:~/home/cpp/break$ -- Simon Burton, B.Sc. Licensed PO Box 8066 ANU Canberra 2601 Australia Ph. 61 02 6249 6940 http://arrowtheory.com

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how to call array with None argument
by Charles R Harris Feb. 26, 2005

Feb. 26, 2005

Hello all, I have noticed that in numarray the call a = array(None,shape=(2,2)) will create a uninitialized array of dimension (2,2). However, I am unable to figure out how to use the array factory in boost to create an array with this call. Anyone have suggestions? Chuck

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Exception Handling - What class is thrown?
by Clay Culver Feb. 23, 2005

Feb. 23, 2005

I'm trying to handle exceptions that occur within an embedded script. Here's the code I'm basing this off of: try { // This will fail. handle<>(PyRun_String( "not_a_variable", Py_file_input, pyNamespace.ptr(), pyNamespace.ptr() )).reset(); } catch (...) { PyErr_Clear( ); } That fails since not_a_variable hasn't been defined yet. What I'd like to do is catch the exception and report the problem to the user. The information about the error I can get using the Python/C api, but I can't figure out what class is actually being thrown so that I can replace the (...) with the actual class. What is this class? I've also been digging around the Boost.Python documentation, and I see a lot of information about converting exceptions, but I can't seem to find where the exceptions thrown by Boost.Python are documented. Are those contained in one place? Thanks! Clay

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Multiple python interpreter contexts
by Clay Culver Feb. 23, 2005

Feb. 23, 2005

I'm trying to make two separate contexts for my embedded python application. That is, if I set some the X variable in one, it does not set X in the other. I tried to do this by copying the dictionary like this: object mainModule(handle<>(borrowed(PyImport_AddModule("__main__")))); dict pyNamespace = dict(mainModule.attr("__dict__")); dict pyNamespace2 = dict(pyNamespace); handle<> result(PyRun_String( "test = 1\n", Py_file_input, pyNamespace.ptr(), pyNamespace.ptr()) ); handle<> result2(PyRun_String( "test = 2\n", Py_file_input, pyNamespace2.ptr(), pyNamespace2.ptr()) ); handle<> result3(PyRun_String( "print test\n", Py_file_input, pyNamespace.ptr(), pyNamespace.ptr()) ); handle<> result4(PyRun_String( "print test\n", Py_file_input, pyNamespace2.ptr(), pyNamespace2.ptr()) ); But this always prints out 2, 2 instead of 1, 2 like I want it to. What am I doing wrong here? Thanks, Clay

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Idea: Injecting methods using Python 2.4 decorator syntax
by Ralf W. Grosse-Kunstleve Feb. 20, 2005

Feb. 20, 2005

With reference to my previous posting http://mail.python.org/pipermail/c++-sig/2005-February/008585.html and this section in the Boost.Pyton documentation http://www.boost.org/libs/python/doc/tutorial/doc/html/python/techniques.ht… Here is a neat alternative based on Python 2.4 decorators: # general purpose helper for injecting attributes class injector: def __init__(self, obj, attr): self.obj = obj self.attr = attr def __call__(self, attr_obj): setattr(self.obj, self.attr, attr_obj) class point: def __init__(self, (x,y)): self.xy = (x,y) @injector(point, "__str__") def attr_obj(self): return str(self.xy) p = point((1,2)) print p I am not sure about all the pros and cons compared to the BoostPythonMetaclass approach shown in the Boost.Python documentation, but at least I find it easier to understand and the injector is completely independent of Boost.Python. Cheers, Ralf __________________________________ Do you Yahoo!? The all-new My Yahoo! - What will yours do? http://my.yahoo.com

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functions not showing up in pydoc
by Nick Rasmussen Feb. 18, 2005

Feb. 18, 2005

I'm running into a problem with functions at the module level not showing up in pydoc. The problem is that the type of the function object in the module is: >>> type(testfoo.foo) <type 'Boost.Python.function'> Which isn't a sublcass of <type 'builtin_function_or_method'> When pydoc walks the module it only documents routines that are either builtin (according to inspect.isbuiltin) or are objects whose module can be deduced via inspect.getmodule. I modified function.cpp with: --- libs/python/src/object/function.cpp.orig 2005-02-07 17:11:52.000066304 -0800 +++ libs/python/src/object/function.cpp 2005-02-07 16:55:24.000120507 -0800 @@ -608,7 +608,7 @@ 0, /* tp_methods */ 0, // func_memberlist, /* tp_members */ function_getsetlist, /* tp_getset */ - 0, /* tp_base */ + &PyCFunction_Type, /* tp_base */ 0, /* tp_dict */ function_descr_get, /* tp_descr_get */ 0, /* tp_descr_set */ and it seemed to fix it. Is this right, or is there a different way that functions should get exposed such that pydoc can understand them? Also, for functions with overloads, only one of the docstrings is printed out. It looks like void function::add_to_namespace( object const& name_space, char const* name_, object const& attribute, char const* doc) just replaces the old doc string instead of appending the new one to the old. -nick

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