How can I use a decorated name with

I'm writing a library which lets the user decorate the function names like this:

#ifndef DECORATE // Define this before including if you want to change the names.
#define DECORATE(name) lib_##name
#endif

I now what to use _Generic to create a generic function foo like this:

#define DECORATE(foo)(x)            \
    _Generic((x),                   \
             int:   DECORATE(fooi), \
             float: DECORATE(foof)  \
    )(x)

This of course gives me an error, because I can't define the DECORATE macro twice. Is there a way to decorate the name of the generic function or is this impossible?

CodePudding user response：

You need to give your macros two different names so one can use the other. Also, in the case of the one using _Generic, both parameters need to be in one set of parenthesis separated by spaces.

#ifndef DECORATEX 
#define DECORATEX(name) lib_##name
#endif

#define DECORATE(foo,x)            \
    _Generic((x),                   \
             int:   DECORATEX(foo##i), \
             float: DECORATEX(foo##f)  \
    )(x)


void lib_abci(int x)
{
    printf("in abci, x=%d\n", x);
}

void lib_abcf(float x)
{
    printf("in abcf, x=%f\n", x);
}

int main()
{
    int a=3;
    float b=4.5;
    DECORATE(abc,a);
    DECORATE(abc,b);
    return 0;
}

Output:

in abci, x=3
in abcf, x=4.500000