Opaque-Handle-Muster zur strukturellen Datenkapselung

#include <stdio.h>
#include <stdlib.h>
 
typedef struct WidgetImpl* WidgetHandle;
 
struct WidgetImpl {
    int id;
    char name[32];
};
 
WidgetHandle widget_create(int id) {
    struct WidgetImpl* w = (struct WidgetImpl*)malloc(sizeof(struct WidgetImpl));
    if (!w) return NULL;
    w->id = id;
    snprintf(w->name, sizeof(w->name), "Widget-%d", id);
    return w;
}
 
void widget_process(WidgetHandle handle) {
    if (!handle) return;
    printf("Processing %s (ID: %d)\n", handle->name, handle->id);
}
 
void widget_destroy(WidgetHandle handle) {
    free(handle);
}
 
int main(void) {
    WidgetHandle w = widget_create(101);
    widget_process(w);
    widget_destroy(w);
    return 0;
}