main.c

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

typedef enum {
    GENDER_NEUTRAL,
    GENDER_MALE,
    GENDER_FEMALE,
    GENDER_UNKNOWN,
} gender;

char *
gender_string(gender gen)
{
    switch (gen) {
    case GENDER_NEUTRAL:
        return "Neutral";
    case GENDER_MALE:
        return "Male";
    case GENDER_FEMALE:
        return "Female";
    case GENDER_UNKNOWN:
        return "Unknown";
    }
}

typedef struct _person {
    char *name;
    gender gen;

    void (*set_name)(struct _person *receiver, char *name);
    void (*set_gender)(struct _person *receiver, gender gen);
    void (*print)(struct _person receiver);
} person;

void person_set_name(person *receiver, char *name);
void person_set_gender(person *receiver, gender gen);
void person_print(person receiver);

person*
new_person()
{
    person *p = (person *)malloc(sizeof(person));
    p->name = NULL;
    p->gen = GENDER_UNKNOWN;
    p->set_name = person_set_name;
    p->set_gender = person_set_gender;
    p->print = person_print;
    return p;
}

void
free_person(person *p)
{
    if (NULL != p)
    {
        free(p);
        p = NULL;
    }
}

void
person_set_name(person *receiver, char *name)
{
    receiver->name = name;
}

void
person_set_gender(person *receiver, gender gen)
{
    receiver->gen = gen;
}

void
person_print(person receiver)
{
    printf("%s %s\n", receiver.name, gender_string(receiver.gen));
}

int
main(int argc, char* argv[])
{
    person *p = new_person();
    p->set_name(p, "kaneshin");
    p->set_gender(p, GENDER_MALE);
    p->print(*p);
    free_person(p);
    return 0;
}