[C++-sig] Wrapping and Passing HWND with Boost.Python
Hello,
I've created a Boost.Python wrapper (using Py++) for a C++ legacy class
that takes a HWND window handle in its constructor. However, after
exporting the module to python when I try to use it, I get a type mismatch
error.
--
Here is the C++ class I'm wrapping:
// File Foo.hpp
//
#include "Windows.h"
class Foo
{
public:
Foo( const HWND window ){}
virtual ~Foo(){}
virtual int Bar( int num ) { return num; }
};
--
The Py++ output:
INFO Parsing source file "foo.hpp" ...
INFO gccxml cmd: ""c:\Program Files (x86)\gccxml 0.9\bin\gccxml.exe"
-I"." "foo.hpp" -fxml="d:\temp\tmpdng3ts.xml""
INFO GCCXML version - 0.9( 1.127 )
INFO: file "generated_wrapper.cpp" - updated( 0.001607 seconds )
--
The generated wrapper:
#include "boost/python.hpp"
#include "foo.hpp"
namespace bp = boost::python;
struct Foo_wrapper : Foo, bp::wrapper< Foo > {
Foo_wrapper(::HWND const window )
: Foo( window )
, bp::wrapper< Foo >(){
// constructor
}
virtual int Bar( int num ) {
if( bp::override func_Bar = this->get_override( "Bar" ) )
return func_Bar( num );
else{
return this->Foo::Bar( num );
}
}
int default_Bar( int num ) {
return Foo::Bar( num );
}
};
BOOST_PYTHON_MODULE(MyWrapper){
{ //::Foo
typedef bp::class_< Foo_wrapper > Foo_exposer_t;
Foo_exposer_t Foo_exposer = Foo_exposer_t( "Foo", bp::init<
HWND__ *>(( bp::arg("window") )) );
bp::scope Foo_scope( Foo_exposer );
bp::implicitly_convertible< const HWND, Foo >();
{ //::Foo::Bar
typedef int ( ::Foo::*Bar_function_type )( int ) ;
typedef int ( Foo_wrapper::*default_Bar_function_type )(
int ) ;
Foo_exposer.def(
"Bar"
, Bar_function_type(&::Foo::Bar)
, default_Bar_function_type(&Foo_wrapper::default_Bar)
, ( bp::arg("num") ) );
}
}
}
--
In python I get the not-match error:
>>> import MyWrapper
>>> import win32gui
>>> hwnd = win32gui.GetDesktopWindow()
>>> foo = MyWrapper.Foo(hwnd)
Traceback (most recent call last):
File "", line 1, in
Boost.Python.ArgumentError: Python argument types in
Foo.__init__(Foo, int)
did not match C++ signature:
__init__(struct _object *, struct HWND__ * window)
>>>
How can I correct this problem to be able to pass a window's handle (from
win32gui) in Python to C++ class, and interact with it?
Environment:
Visual Studio 2008, Boost 1.44, gcc-xml 0.9.0, py++ 1.0.0, pygccxml 1.1.0
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Re: [C++-sig] Wrapping and Passing HWND with Boost.Python
Thanks Roman for your quick reply, That's what confuses me. HWND is essentially a pointer to an int to hold the window handle. How can to convert them to each other? Ehsan On Mon, Apr 30, 2012 at 2:46 PM, Roman Yakovenko wrote: > On Mon, Apr 30, 2012 at 9:11 PM, Ehsan Pi wrote: > > In python I get the not-match error: > > > > >>> import MyWrapper > > >>> import win32gui > > >>> hwnd = win32gui.GetDesktopWindow() > > >>> foo = MyWrapper.Foo(hwnd) > > Traceback (most recent call last): > > File "", line 1, in > > Boost.Python.ArgumentError: Python argument types in > > Foo.__init__(Foo, int) > > did not match C++ signature: > > __init__(struct _object *, struct HWND__ * window) > > >>> > > > > How can I correct this problem to be able to pass a window's handle (from > > win32gui) in Python to C++ class, and interact with it? > > I think the error is pretty clear: the exported constructor expects a > pointer to some struct(?) HWND__, while, win32gui returns the handle > as integer. You will have to find some way to associate handle as > integer with handle as HWND__. Once you find it, you can use > "make_constructor" functionality, which is also supported by py++. > > HTH. > ___ > Cplusplus-sig mailing list > Cplusplus-sig@python.org > http://mail.python.org/mailman/listinfo/cplusplus-sig > ___ Cplusplus-sig mailing list Cplusplus-sig@python.org http://mail.python.org/mailman/listinfo/cplusplus-sig
Re: [C++-sig] Wrapping and Passing HWND with Boost.Python
Thanks Niall for your response and correction on HWND. I'm new to Python (and Boost.Python for that matter) and thought Python was not typed. If not, how can one convert Python integers to void*? Googled but didn't find an answer. Regards, Ehsan On Tue, May 1, 2012 at 9:18 AM, Niall Douglas wrote: > A HWND is always a void * i.e. an opaque pointer. Unfortunately some > people using BPL think that BPL can't handle opaque pointers, so they > do fun stuff like use a thunk struct type for void * instead, and > wrap the lot in manual pointer casting. It's far easier just to > declare it an opaque pointer and be done with it. > > It is very unfortunate indeed that win32gui returns a HWND as an > integer. It isn't an integer and must not be treated as one. Still, > it's easy to write a routine which converts python integers to void > *. > > Niall > > > On 30 Apr 2012 at 14:54, Ehsan Pi wrote: > > > Thanks Roman for your quick reply, > > > > That's what confuses me. HWND is essentially a pointer to an int to hold > > the window handle. How can to convert them to each other? > > > > Ehsan > > > > On Mon, Apr 30, 2012 at 2:46 PM, Roman Yakovenko > > wrote: > > > > > On Mon, Apr 30, 2012 at 9:11 PM, Ehsan Pi wrote: > > > > In python I get the not-match error: > > > > > > > > >>> import MyWrapper > > > > >>> import win32gui > > > > >>> hwnd = win32gui.GetDesktopWindow() > > > > >>> foo = MyWrapper.Foo(hwnd) > > > > Traceback (most recent call last): > > > > File "", line 1, in > > > > Boost.Python.ArgumentError: Python argument types in > > > > Foo.__init__(Foo, int) > > > > did not match C++ signature: > > > > __init__(struct _object *, struct HWND__ * window) > > > > >>> > > > > > > > > How can I correct this problem to be able to pass a window's handle > (from > > > > win32gui) in Python to C++ class, and interact with it? > > > > > > I think the error is pretty clear: the exported constructor expects a > > > pointer to some struct(?) HWND__, while, win32gui returns the handle > > > as integer. You will have to find some way to associate handle as > > > integer with handle as HWND__. Once you find it, you can use > > > "make_constructor" functionality, which is also supported by py++. > > > > > > HTH. > > > ___ > > > Cplusplus-sig mailing list > > > Cplusplus-sig@python.org > > > http://mail.python.org/mailman/listinfo/cplusplus-sig > > > > > > > > -- > Technology & Consulting Services - ned Productions Limited. > http://www.nedproductions.biz/. VAT reg: IE 9708311Q. > Work Portfolio: http://careers.stackoverflow.com/nialldouglas/ > > > > ___ > Cplusplus-sig mailing list > Cplusplus-sig@python.org > http://mail.python.org/mailman/listinfo/cplusplus-sig > ___ Cplusplus-sig mailing list Cplusplus-sig@python.org http://mail.python.org/mailman/listinfo/cplusplus-sig
Re: [C++-sig] Wrapping and Passing HWND with Boost.Python
Thanks Roman, I believe these are not specific to py++ but boost.python, correct? What I mean is whether it can be automated through the py++ wrapper, or do I have to manually alter the py++ generated cpp file? Regards, Ehsan On Mon, Apr 30, 2012 at 3:00 PM, Roman Yakovenko wrote: > On Mon, Apr 30, 2012 at 9:54 PM, Ehsan Pi wrote: > > Thanks Roman for your quick reply, > > > > That's what confuses me. HWND is essentially a pointer to an int to hold > the > > window handle. How can to convert them to each other? > > I am not sure that you are right, but in case you are, use > make_constructor and reinterpret_cast. > > Regards, > Roman > ___ > Cplusplus-sig mailing list > Cplusplus-sig@python.org > http://mail.python.org/mailman/listinfo/cplusplus-sig > ___ Cplusplus-sig mailing list Cplusplus-sig@python.org http://mail.python.org/mailman/listinfo/cplusplus-sig
Re: [C++-sig] Wrapping and Passing HWND with Boost.Python
Thanks again. I'll give it a try as soon as I get a chance. On Tue, May 1, 2012 at 10:37 AM, Roman Yakovenko wrote: > On Tue, May 1, 2012 at 5:25 PM, Ehsan Pi wrote: > > Thanks Roman, > > > > I believe these are not specific to py++ but boost.python, correct? > > Yes > > > What I > > mean is whether it can be automated through the py++ wrapper, or do I > have > > to manually alter the py++ generated cpp file? > > Yes. py++ supports opaque pointers and code injection. The > documentation contains explanation for different use cases. > ___ > Cplusplus-sig mailing list > Cplusplus-sig@python.org > http://mail.python.org/mailman/listinfo/cplusplus-sig > ___ Cplusplus-sig mailing list Cplusplus-sig@python.org http://mail.python.org/mailman/listinfo/cplusplus-sig
[C++-sig] Boost.Python: How to fill a passed in buffer in Python
Hello forum,
I have a buffer in C++ that I need to fill in Python. The Address of the
buffer is obtained through the GetAddress method which returns a void
pointer to the buffer address.
#include
class Foo
{
public:
Foo(const unsigned int length)
{
m_buffer = boost::shared_ptr< unsigned char >( new unsigned
char[ length ] );
}
~Foo(){}
void* GetAddress( ) const
{
// cast for the sake of this question
return reinterpret_cast< void* >( m_buffer.get() );
}
private:
boost::shared_ptr< unsigned char > m_buffer;
Foo();
Foo(const Foo&);
};
Using Py++ I can generate the Boost.Python wrapper to export the class to
Python as follows:
#include "boost/python.hpp"
#include "foo.hpp"
namespace bp = boost::python;
BOOST_PYTHON_MODULE(MyWrapper){
{ //::Foo
typedef bp::class_< Foo, boost::noncopyable > Foo_exposer_t;
Foo_exposer_t Foo_exposer = Foo_exposer_t( "Foo", bp::init<
unsigned int >(( bp::arg("length") )) );
bp::scope Foo_scope( Foo_exposer );
bp::implicitly_convertible< unsigned int const, Foo >();
{ //::Foo::GetAddress
typedef void * ( ::Foo::*GetAddress_function_type )( )
const;
Foo_exposer.def(
"GetAddress"
, GetAddress_function_type( &::Foo::GetAddress )
, bp::return_value_policy< bp::return_opaque_pointer
>() );
}
}
}
In Python, the output of the GetAddress is a void * to the memory address:
>>> import MyWrapper
>>> foo = MyWrapper.Foo(100)
>>> address = foo.GetAddress()
>>> print address
>>>
My question is can I fill the buffer in Python, and if so how?
Thanks a lot,
Ehsan
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