Abstrakte Schnittstellen-Verteilung über VTable-Struktur-Zeiger

#include <stdio.h>
 
typedef struct LoggerVTable LoggerVTable;
 
typedef struct {
    const LoggerVTable *vtable;
} Logger;
 
struct LoggerVTable {
    void (*log)(Logger *self, const char *msg);
};
 
typedef struct {
    Logger base;
    const char *prefix;
} ConsoleLogger;
 
static void console_log_impl(Logger *self, const char *msg) {
    ConsoleLogger *cl = (ConsoleLogger *)self;
    printf("[%s] %s\n", cl->prefix, msg);
}
 
static const LoggerVTable CONSOLE_LOGGER_VTABLE = {
    .log = console_log_impl
};
 
void console_logger_init(ConsoleLogger *cl, const char *prefix) {
    cl->base.vtable = &CONSOLE_LOGGER_VTABLE;
    cl->prefix = prefix;
}
 
void logger_dispatch(Logger *logger, const char *msg) {
    if (logger && logger->vtable && logger->vtable->log) {
        logger->vtable->log(logger, msg);
    }
}