[PyQt] Fwd: Re: c++ app integrate PyQt

[John Fabiani]

On 10/01/2013 11:52 AM, Matt Newell wrote:
>> That sounds encouraging.  But it lacks a little detail - like how does
>> one embed python (PyQt) into a C++ app.  The sip I sort of understand
>> and it is doable.  I only need a few C++ classes and that makes sense.
>> But I don't have a clue how or where to start on embeding PyQt.  Does
>> someone have an example or a link explaining the details.
>>
>> Johnf
> The embedding is really not very involved.  Here is a snippet of code from one
> of my apps, with some irrelevant stuff removed.  This both initializes python,
> and loads CWD/plugins as a python module where you can load whatever you want
> from the __init__.py, including submodules.
>
> Matt
>
> // Return the named attribute object from the named module.
> // Returns a NEW reference(PyObject_GetAttrString)
> PyObject * getModuleAttr(const char *module, const char *attr)
> {
> #if PY_VERSION_HEX >= 0x02050000
>      PyObject *mod = PyImport_ImportModule(module);
> #else
>      PyObject *mod = PyImport_ImportModule(const_cast<char *>(module));
> #endif
>
>      if (!mod)
>      {
>          PyErr_Print();
>          return 0;
>      }
>
> #if PY_VERSION_HEX >= 0x02050000
>      PyObject *obj = PyObject_GetAttrString(mod, attr);
> #else
>      PyObject *obj = PyObject_GetAttrString(mod, const_cast<char *>(attr));
> #endif
>
>      Py_DECREF(mod);
>
>      if (!obj)
>      {
>          PyErr_Print();
>          return 0;
>      }
>
>      return obj;
> }
>
> void loadPythonPlugins()
> {
> 	
> 	Py_Initialize();
> 	PyEval_InitThreads();
> 	
> 	PyObject * sys_path = getModuleAttr("sys", "path");
>
> 	if (!sys_path) {
> 		LOG_1( "Python Initialization Failure: Failed to get sys.path" );
> 		return;
> 	}
> 	
> 	QString dir = QDir::currentPath();
> 	
> 	// Convert the directory to a Python object with native separators.
> #if QT_VERSION >= 0x040200
> 	dir = QDir::toNativeSeparators(dir);
> #else
> 	dir = QDir::convertSeparators(dir);
> #endif
>
> #if PY_MAJOR_VERSION >= 3
> 	// This is a copy of qpycore_PyObject_FromQString().
>
> 	PyObject *dobj = PyUnicode_FromUnicode(0, dir.length());
>
> 	if (!dobj)
> 	{
> 		PyErr_Print();
> 		return;
> 	}
>
> 	Py_UNICODE *pyu = PyUnicode_AS_UNICODE(dobj);
>
> 	for (int i = 0; i < dir.length(); ++i)
> 		*pyu++ = dir.at(i).unicode();
> #else
> 	PyObject *dobj = PyString_FromString(dir.toAscii().constData());
>
> 	if (!dobj)
> 	{
> 		PyErr_Print();
> 		return;
> 	}
> #endif
>
> 	// Add the directory to sys.path.
> 	int rc = PyList_Append(sys_path, dobj);
> 	Py_DECREF(dobj);
> 	Py_DECREF(sys_path);
> 	
> 	if (rc < 0)
> 	{
> 		PyErr_Print();
> 		return;
> 	}
>
> 	PyObject *plug_mod = PyImport_ImportModule("plugins");
> 	if (!plug_mod)
> 	{
> 		PyErr_Print();
> 		return;
> 	}
> 	Py_DECREF(plug_mod);
> 	
> 	PyEval_SaveThread();
> }
Thanks I'll take a look later today.

Johnf