Re: Objectizing C Code

From:

cbarron3@ix.netcom.com (Carl Barron)

Newsgroups:

comp.lang.c++.moderated

Date:

Mon, 26 Feb 2007 21:21:03 CST

Message-ID:

<1hu5skn.10yc3elwtfeqaN%cbarron3@ix.netcom.com>

Robby <rsimpson@gmail.com> wrote:

Here's a brainteaser:

I have some legacy C code that I cannot modify for various reasons. I
would like to be able to wrap this code into a C++ class so that I can
create multiple objects to interact with.

To simplify, here's some code:

======================================================
foo.h (Can't modify):

#ifndef _FOO_H_
#define _FOO_H_

#if defined(TEST1) && defined(TEST2)
#error "Cannot define both TEST1 and TEST2"
#endif

#ifdef TEST1
#define OUTVAR 1
#elif defined(TEST2)
#define OUTVAR 2
#else
#error "Need TEST1 or TEST2"
#endif

extern int testInt;

void testFunc();

#endif

======================================================
======================================================
foo.c (Cannot modify):

#include "foo.h"
#include <stdio.h>

int testInt;

void testFunc() {
testInt = OUTVAR;
printf("%d\n", testInt);
}

======================================================

// wrapper.h"
#ifndef WRAPPER_H_INCLUDED
#define WRAPPRE_H_INCLUDED
extern "C"
{
#include "foo.h"
}

template <int N>
struct wrapper
{
    int var;
    void operator () ()
    {
       testFunc();
       var = testInt;
    }
};

#endif

usage:
    wrapper<OUTVAR> functor;
    functor();
    int local_copy = functor.var;

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