Re: Batch of unsolved external symbols

[Barry S. <ba...@ba...>]

On Thursday 05 November 2015 18:19:13 Ilçeren Inçelami Çadormoç wrote:
> Good afternoon,I've came across this PyCXX project just recently as I was
> looking for information on how to make extension modules for Python so I
> could hook up some C++ code to a Python back-end. I've used the
> "example.cxx" file heavily for reference in order to code the interface
> with Python using an ExtensionModule, added the path to the installation
> folder for the header inclusion, included the necessary headers at the
> start of my code and added the three PyCXX code files required for
> extension programming to my sources directory. The thing is, even then, I
> get a bunch of unresolved external symbols when I try to compile my program
> to a DLL file. I'm using Visual Studio 2010. I don't think I've forgotten
> anything, not after re-reading the installation and module sections of the
> documentation a few times. The errors are as follow:
> 
> Error	24	error LNK2001: símbolo externo "void __cdecl Py::_XINCREF(struct
> _object *)" (?_XINCREF@Py@@YAXPEAU_object@@@Z) sin
> resolver	C:\...\cxxsupport.obj	Hephestos Hammer Error	21	error 
LNK2001:
> símbolo externo "void __cdecl Py::_XDECREF(struct _object *)"
> (?_XDECREF@Py@@YAXPEAU_object@@@Z) sin
> resolver	C:\...\cxxsupport.obj	Hephestos Hammer Error	41	error 
LNK2001:
> símbolo externo "struct _typeobject * __cdecl Py::_Type_Type(void)"
> (?_Type_Type@Py@@YAPEAU_typeobject@@XZ) sin
> resolver	C:\...\cxx_extensions.obj	Hephestos Hammer Error	39	error 
LNK2001:
> símbolo externo "struct _object * __cdecl Py::_None(void)"
> (?_None@Py@@YAPEAU_object@@XZ) sin
> resolver	C:\...\cxx_extensions.obj	Hephestos Hammer Error	36	error 
LNK2001:
> símbolo externo "struct _object * __cdecl Py::_Exc_TypeError(void)"
> (?_Exc_TypeError@Py@@YAPEAU_object@@XZ) sin
> resolver	C:\...\cxxsupport.obj	Hephestos Hammer Error	42	error 
LNK2001:
> símbolo externo "struct _object * __cdecl Py::_Exc_RuntimeError(void)"
> (?_Exc_RuntimeError@Py@@YAPEAU_object@@XZ) sin
> resolver	C:\...\cxx_extensions.obj	Hephestos Hammer Error	47	error 
LNK2001:
> símbolo externo "char * __cdecl Py::__Py_PackageContext(void)"
> (?__Py_PackageContext@Py@@YAPEADXZ) sin
> resolver	C:\...\cxx_extensions.obj	Hephestos Hammer Error	27	error 
LNK2001:
> símbolo externo "bool __cdecl Py::_Unicode_Check(struct _object *)"
> (?_Unicode_Check@Py@@YA_NPEAU_object@@@Z) sin
> resolver	C:\...\cxxsupport.obj	Hephestos Hammer Error	30	error 
LNK2001:
> símbolo externo "bool __cdecl Py::_Type_Check(struct _object *)"
> (?_Type_Check@Py@@YA_NPEAU_object@@@Z) sin
> resolver	C:\...\cxxsupport.obj	Hephestos Hammer Error	31	error 
LNK2001:
> símbolo externo "bool __cdecl Py::_String_Check(struct _object *)"
> (?_String_Check@Py@@YA_NPEAU_object@@@Z) sin
> resolver	C:\...\cxxsupport.obj	Hephestos Hammer Error	34	error 
LNK2001:
> símbolo externo "bool __cdecl Py::_List_Check(struct _object *)"
> (?_List_Check@Py@@YA_NPEAU_object@@@Z) sin
> resolver	C:\...\cxxsupport.obj	Hephestos Hammer Error	48	error 
LNK2001:
> símbolo externo "bool __cdecl Py::_Int_Check(struct _object *)"
> (?_Int_Check@Py@@YA_NPEAU_object@@@Z) sin
> resolver	C:\...\thirdeye.obj	Hephestos Hammer Error	46	error 
LNK2001:
> símbolo externo "bool __cdecl Py::_Dict_Check(struct _object *)"
> (?_Dict_Check@Py@@YA_NPEAU_object@@@Z) sin
> resolver	C:\...\cxx_extensions.obj	Hephestos Hammer
> 
> The Spanish bits just mean "Unresolved external symbol". I've also skipped
> some duplicated errors since I have to copy each one manually and there are
> some which are repeated up to three times in different .obj files. I don't
> know how to fix them, since I don't find anywhere the functions are
> defined. For example, I can track the Py::_XINCREF and Py::_XDECREF errors
> to the Objects.hxx file, where those functions are called, but none of the
> other files have a definition of said functions, it seems... Am I missing
> something?

The missing symbols are in IndirectPythonInterface.cxx
It is not optional.

You can generate a windows make file using the following:

c:\python27\python.exe setup_makefile.py win32 example.mak

change the path to python to suit your needs.

If you have nmake on the path you can then build the examples

nmake -f example.make

Barry