Re: Choose between class implementations at compiletime

From:
"Chris M. Thomasson" <no@spam.invalid>
Newsgroups:
comp.lang.c++
Date:
Fri, 11 Sep 2009 16:24:08 -0700
Message-ID:
<h8em4k$14eq$1@news.ett.com.ua>
"Christoph Mathys" <cmathys@gmail.com> wrote in message
news:24a9e72f-9f2a-4974-9561-6b75c6c21193@g23g2000yqh.googlegroups.com...

Hello!

Well, nothing too spectacular, but I'd still be interested in how one
solves this problem in a clean way: I need to a implement a class
which uses different APIs and provides a uniform interface (APIs are
fixed at compiletime). I can't use an ABC directly because the class
is only used as value type. But I'd still like to have an interface
common to all classes, defined at a single place.


[...]

Perhaps you could try something like:

<pseudo-code typed in newsreader>
________________________________________________________________
// your_lib_windows.hpp
#include <windows.h>

namespace your_lib_windows
{
    class mutex
    {
        CRITICAL_SECTION m_mutex;

    public:
        void lock() throw() {...}

        void unlock() throw() {...}
    };
}

namespace your_lib_os = your_lib_windows;

// your_lib_posix.hpp
#include <pthread.h>

namespace your_lib_posix
{
    class mutex
    {
        pthread_mutex_t m_mutex;

    public:
        void lock() throw() {...}

        void unlock() throw() {...}
    };
}

namespace your_lib_os = your_lib_posix;

// your_lib.hpp
#if defined (WINDOWS_PLATFORM)
# include "your_lib_windows.hpp"
#elif defined (POSIX_PLATFORM)
# include "your_lib_posix.hpp"
#else
# error Platform Not Supported!
#endif

namespace your_lib
{
    namespace os = your_lib_os;
}

// main.cpp
#include "your_lib.hpp"

int main()
{
    {
        your_lib::os::mutex mtx;

        mtx.lock();

        mtx.unlock();
    }

    return 0;
}

________________________________________________________________

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