Extending/Embedding python

[Robert M. Emmons]

> Thanks for any help that can be offered.  I've been working with Python for
> a year or more now, but only doing simple extending in C/C++.  I'm now
> attempting some embedding and several questions have come to mind.

Your ahead of me!

> BTW - I'm running Windows 2000 with Python23 and VisualC++ developers
> studio.

I won't hold that against you.  :)

> 1.  (Not extending/embedding related at all)  How can I pass in a load/bunch
> of defines so I can use them over and over again, instead of having to copy
> them in every *.py script.  All my scripts use an "extension" dll that I
> wrote that require a lot of constants.  I looked a lot at that PyMemberDef
> and Type stuff but didn't get it and don't know if that's the solution
> anyway.

Why not just import these with a single import at the top of your python 
script.  There is probably also a way to make C do this to setup the 
name space first too.

> 2.  A couple simple examples I've seen for initModule() are written
> differently.  One only calls Py_InitModule("module", module_methods), but
> the other also calls PyImport_AddModule("module").  What is the difference?
> What does PyImport_AddModule() accomplish?

Can't help you there.  I don't know much about actual embedding.

> 3.  When embedding Python into my simple application, why can't I pass
> application parameters?  PyRun_SimpleString seems to only take hard-coded
> values.  Can/How can I get around this?  My code looks like:
> 
>   if (!Py_IsInitialized())
>   {
>    Py_Initialize();
>   }
>   PyRun_SimpleString("import MyModule");
>   PyRun_SimpleString("MyModule.init(1, 'c:\\diag\\dsp.ldr', 0x5555)");
>   PyRun_SimpleString("MyModule.MemoryTest(1, 0, 1)");
>   PyRun_SimpleString("MyModule.Shutdown()");
>   Py_Finalize();
> 
> But I'd like to pass application variables instead of the hard-coded 1, 0, 1
> and 0x5555, such as:
> 
> int appInt = 0x5555;
> PyRun_SimpleString("MyModule.init(1, 'c:\\diag\\dsp.ldr', appInt)");
> 
> I know I'm missing something fundamental here.  Please advise.

I'm not certain this is what you mean -- but if by appInt -- you mean 
appInt is defined in the C code, then you need to convert it's value 
into a string then send it as a value like you were alread able to do. 
I'm not embedding expert but it looks like the "SimpleString" procedure 
is just sending python code as text.

The other thing is that if you want to pass down actual variable data 
into python it probably has to be coded as a python object -- remember 
that python and C don't use the same data construct's, all of these must 
be converted and the embedding stuff has routines to do this.

Also as an aside -- you might want to just make an ActiveX/COM extension 
rather than dong embedding if your just using windows.  See the book 
Python Programming on Win32 to see how.

Rob