#include <stdio.h>

struct fs_operation {
    void (*read)(void);
    void (*write)(void);
};

struct file_system {
    char fs_name[64];
    struct fs_operation fops;       //相当于C++中的纯虚函数，再定义的时候具体赋值，再通过指针调用，实现多态
};

void ext4_read(void)
{
    printf("%s\n", __func__);
}

void ext4_write(void)
{
    printf("%s\n", __func__);
}

void nfs_read(void)
{
    printf("%s\n", __func__);
}

void nfs_write(void)
{
    printf("%s\n", __func__);
}

int main()
{
    struct file_system ext4 = {     //子类ext4
        .fs_name = "ext4",
        .fops.read = ext4_read,
        .fops.write = ext4_write,
    };

    struct file_system nfs = {      //子类nfs
        .fs_name = "nfs",
        .fops.read = nfs_read,
        .fops.write = nfs_write,
    };

    struct file_system* pfs;        //定义一个指向基类的指针
    pfs = &ext4;                    //基类指针指向子类 ext4
    pfs->fops.read();               //和下面一起实现了多态

    pfs = &nfs;
    pfs->fops.read();

    return 0;
}