Converting a C++ class to a C struct (and beyond)

Question

Past few days I have been \"downgrading\" > 1000 filem of C++ code into C. It\'s been going well until now. Suddenly I\'m face to face with a class...

The compiler

Answer 1

Turn foobar into a normal struct

struct foobar {
    goo mutex;
};

Create your own "constructor" and "destructor" as functions that you call on that struct

void InitFoobar(foobar* foo)
{
   oneCreate(&foo->mutex);
}

void FreeFoobar(foobar* foo)
{
   oneDestroy(foo->mutex);
}

struct foobar fooStruct;
InitFoobar(&fooStruct);
// ..
FreeFoobar(&fooStruct);

etc

Answer 2

since C-structs can't have member functions, you can either make function pointers, or create non-member versions of those functions, ex:

struct foobar {
    foo mutex;
};

Construct_foobar(foobar* fooey) {
    oneCreate(&fooey->mutex, NULL);
}
Destroy_foobar(foobar* fooey) {
    oneDestroy(fooey->mutex);
    fooey->mutex = NULL;
}
void ObtainControl(foobar* fooey) {
    oneAcquire(fooey->mutex);
}
void ReleaseControl(foobar* fooey) {
    oneRelease(fooey->mutex);
}

and in the .C file:

foobar fooey;
construct_foobar( &fooey );
ObtainControl( &fooey );

Answer 3

There are actually compilers that compile from C++ to C. The output is not meant for human digestion, though, see How to convert C++ Code to C.

Answer 4

It depends on your compiler because there isn't a standard way of RAII in C. See this question and the top answer.