[C++-sig] how t o specify and/or update global dictionary for bp::call call

[Gennadiy Rozental]

Stefan Seefeld <seefeld <at> sympatico.ca> writes:

> For avoidance of doubt: you are saying the import itself was successful, 
> but there was no 'foo' symbol in the global namespace after that point ?

Yes. That's true

> I just modified the exec.cpp test (libs/python/tests/exec.cpp), and it 
> all works like a charm.
> (For reference: go to libs/python/tests/exec.cpp and modify the 
> 'exec_test' function to simulate what you want. Here is the modified 
> script I use:
> 
>   python::object main = python::import("__main__");
>   python::object global(main.attr("__dict__"));
>   python::object result = python::exec(
>     "from embedded_hello import *        \n"
>     "from sys import *                   \n"                             
> //<-- added just to show how to populate the global namespace of the script
>     "class PythonDerived(Base):          \n"
>     "    def hello(self):                \n"
>     "        print platform         \n"                                 
> //<-- use it
>     "        return 'Hello from Python!' \n",
>     global, global);


This only works because you used global dictionary as local. I can't do this for
various reasons, main of which is that I am trying to mimic namespacing, which
is unavailable directly in python. So the local dictionary is the dictionary of
the module I am trying to put this class in.
 
>   python::object PythonDerived = global["PythonDerived"];
>   python::object py_base = PythonDerived();
>   Base& py = python::extract<Base&>(py_base);
>   assert(py.hello() == "Hello from Python!");

So what I need to update global dictionary before hello call here even if it was
not used as local during exec call.

Gennadiy