Newbie needs help with VC6 & filesystem library

From: John B. Williston (yg-boost-users_at_[hidden])
Date: 2002-09-15 18:54:38

Greetings,

Though I'm an "old hand" at C++, I'm a complete newbie when it comes
to Boost. The piece that really caught my eye, in light of my current
project, is the directory iterator. To date, however, I haven't had
any success getting it to compile and function under Win32 with MSVC6,
so I thought I would post here. I first have a couple of general
questions about using Boost, and then one specific question about the
problems with my project at hand.

(1) Is there a "right" way to include Boost stuff with VC6? Adding the
Boost base directory to my list of include directories seems to work
for the official stuff, but it clearly doesn't work for the filesystem
stuff because Directory.h is not in the base\boost directory. I can
put it there myself, of course, but I'm wondering if there is some
intended way to use the beta libraries before they become a part of
the whole.

(2) Is there a "right" way to link Boost stuff with VC6? The
filesystem stuff, like the regex stuff and some other pieces, requires
actual compilation and cannot simply be included as header files. I
have already built all the official libraries using the bjam utility,
but I cannot help noticing they're each stored in hideously long paths
beneath the boost base directory. Is there a "right" directory under
the Boost hierarchy into which the resulting libs should be copied for
ease of inclusion in VC6? Or should I copy them into my project
directories as needed? Or should I simply come up with my own system?

To get to the more specific question, let me explain how I've
addressed (1) and (2) for the time being. Regarding (1), I've copied
Directory.h and Boost.h into the base\boost directory so that they may
be included without changing the existing source code. That was simple
enough. Regarding (2), I've decided to add Directory.cpp to my project
and compile it as a module, rather than try to get the linking to work
externally. Having said that, consider the following code:

#include <windows.h>
#include "boost/directory.h"

int WINAPI WinMain(HINSTANCE hInstance, HINSTANCE hPrevInstance, LPSTR
lpCmdLine, int nCmdShow)
{
        using namespace boost::filesystem;
        std::string strFilename;

        for (dir_it it("./"); it != dir_it(); ++it)
                if (!get<is_hidden>(it))
                        strFilename = *it;

        return 0;
}

This is an extremely minimal test case of integrating the filesystem
stuff into a Win32 application. When compiling the application, I get
the following lengthy and inscrutable (to me, at least) error message:

WinMain.obj : error LNK2001: unresolved external symbol
"__declspec(dllimport) public: __thiscall
boost::filesystem::get<struct
boost::filesystem::is_hidden>::get<struct
boost::filesystem::is_hidden>(class boost::filesystem::dir_it const
&)" (__imp_
??0?$get_at_Uis_hidden_at_filesystem@boost@@@filesystem_at_boost@@QAE_at_ABVdir_it_at_12@@Z)

The error message seems to suggest that the filesystem stuff isn't
available in my project. I find that confusing because the
Directory.cpp module compiles without any errors, and I am thus
inclined to think that, in fact, all of the filesystem stuff is in my
project. Thus, I must also ask the third question:

(3) Can anyone explain to me what I might be doing wrong and, more
importantly, how I might correct it? 

Thanks much to all the Boost authors for an interesting set of tools.
And thanks in advance to any who respond for all the help with my
specific issue.

John