source: doc/theses/aaron_moss_PhD/phd/code/macro-generic.c @ caf06aa

#include <stdlib.h>
#include <stdio.h>

// code is nested in macros

#define list(N) N ## _list

#define list_insert(N) N ## _list_insert

#define list_head(N) N ## _list_head

#define define_list(N, T) \
        struct list(N) { T value; struct list(N)* next; }; \
        \
        void list_insert(N)( struct list(N)** ls, T x ) { \
                struct list(N)* node = malloc(sizeof(struct list(N))); \
                node->value = x; node->next = *ls; \
                *ls = node; \
        } \
        \
        T list_head(N)( const struct list(N)* ls ) { return ls->value; }

define_list(int, int);  // defines int_list
define_list(string, const char*);  // defines string_list

// use is efficient, but syntactically idiosyncratic

int main() {
        struct list(int)* il = NULL;
        list_insert(int)( &il, 42 );
        printf("%d\n", list_head(int)(il));
        
        struct list(string)* sl = NULL;
        list_insert(string)( &sl, "hello" );
        printf("%s\n", list_head(string)(sl));
}