I'm trying (for a few days now) to build a DLL generated from C++ code with boost/python to be used by python. I am a Student from Germany and had mostly to do with Java until now (I wrote some basic OpenGL and gimp filter stuff before in C++). So pardon me in advance for bad english or C++ beginner mistakes. I mean, programming with Java really is a lot more comfortable in comparison to C++. But enough of the skirmish.
The error:
LINK : fatal error LNK1104: File "boost_python-vc110-mt-gd-1_53.lib" could not be openend
My presets:
-using MS Visual Studio 2012 (11.0)
-using boost_1_53_0
-using python2.7 (I heard 3.3 may cause some Problems)
What I did:
Installed python and added it to PATH. Then created a new empty project in VS and a class file "Test.cpp" with following content as described on the boost tutorial page:
char const* greet()
{
return "hello world";
}
#include <boost/python.hpp>
BOOST_PYTHON_MODULE(Test)
{
using namespace boost::python
def("greet", greet);
}
Then came the new part for me, in VS Project Properties:
Configuration Properties > General > Configurationtype > Dynamic Library (.dll)
C/C++ > General > Addition Includedirectories > C:[..]\boost_1_53_0
Linker > General > Additional Library Directories > C:[..]boost_1_53_0\stage\lib
From the error I am assuming i did something wrong with Linker or Include. I also changed the Linker > General > Additional Library Directories to boost_1_53_0\libs because i wasn't sure, but the same error occured. And yes, I correctly included python. I am also not sure if i have to put something else beside python into Linker > Input for boost.
Then I build boost with bjam with no options except msvc-11.0 to be sure to have everything i need (though I read that boost/python doesn't need an extra build) and still got the same error. Can someone help me? I would love to have a step by step description of what to do. I am really despairing of this.
Btw.: I had the same error as this guy a few days before Linker error LNK1104 with 'libboost_filesystem-vc100-mt-s-1_49.lib' then stopped working on it and as I started again I got my brand new error (I can't tell you how this happened).
Since it is looking for a static library, add BOOST_PYTHON_STATIC_LIB flag, go to VS properties -> Preprocessor -> Processor definition, add BOOST_PYTHON_STATIC_LIB flag.
You need to create a "user-config.jam" file that indicates where the python headers and libs can be found by Boost.Build. You can create it in your boost_1_53_0/ directory with the following contents:
# Configure specific Python version.
using python : 2.7
: C:/Python27/python.exe
: C:/Python27/include #directory that contains pyconfig.h
: C:/Python27/libs #directory that contains python27.lib
: <toolset>msvc ;
Then from that boost_1_53_0/ directory you need to invoke b2 like this in order to build the missing library:
b2 toolset=msvc-11.0 --with-python variant=debug runtime-debugging=on link=shared --user-config=user-config.jam stage
(although I would recommend b2 toolset=msvc-11.0 --with-python --user-config=user-config.jam --build-type=complete stage so you can get in one step all the configurations that you might need in the future)
Once you have the libraries you need to add the directories to Visual Studio ( both to boost and to python).
Once you have successfully built the module you need to rename it to Test.pyd (exact name you used in BOOST_PYTHON_MODULE. If you have the python and Boost.Python libraries in your PATH or in your current directory you will be able to use the script in the tutorial:
import Test
print Test.greet()
and get the familiar "hello world".
Note that I'm very thankful for your tries but none of your answers helped. A fellow student then gave the hint for the right answer to me and some steps are really easy, others I don't understand, but it works now.
First Problem was: The new boost 1.53.0 does not work with Python27 or older. I then linked it with Python33 and had the build error removed.
But of course the build version didn't work without an error. As I tried to start my helloboost.py which imports from the .pyd built by VisualStudio and invokes the greet method, the following error occured:
ImportError: DLL load failed: The specified module could not be found.
As i checked the hello_ext.pyd with the dependency walker and wildly copy pasted around, I found out it needs the boost_python-vc110-mt-gd-1_53.dll (probably depending on what you need and built with bjam before) in the same folder. It worked then. Maybe someone can explain why nowhere was explained that I need this dll in the same folder as the pyd (or did I miss something? Is it just because I made a mistake before?)
Anyhow, I'm very glad it works now and hope it helps other people.
You probably will have worked this out by now - however:
When a .exe looks for a .dll to load no path is specified. Therefore a .dll must be in the search path for the file.
Also: I was trying to build 1.49 libs for Visual Studio 2013 - and kept getting the LNK error from my project. I don't know who suggested it on stackoverflow but someone\something gave me the idea to copy build system from a more recent boost which knows how to make .libs for more recent environments. (thank you)
I had to copy the boost build system from a 1.58 after running bootstrap in 1.58, copy b2, bjam and boost-build.jam to the earlier boost folder root to replace the same named files there. Also you will need to copy the later tools\build folder to support the build system.
Noting here in the hope it might help someone else in a similar cituation I found myself in.
See: Search Path Used by Windows to Locate a DLL
