如何在 C function 结构上进行此更改？

Question

I've been trying to emulate Python instance construction on C, but i cant find a way to get the struct name backwards to the function and give it as parameter

typedef struct queue {
    .
    .
    ssize_t (*add)(struct queue *, int);
} queue;

ssize_t add(queue *self, int value)
{
    /* Add a element to the queue */
}

int main(void)
{
    queue *clients = createQueue(5); /* Here i create the queue struct */

    clients.add(5); /* I want to convert this instruction to "clients.add(&clients, 5);" */
}

I've triyed to use macros but I've found i can't use regex or something like that

Answer 1

It is difficult to 'emulate' an object language in a non object language like C, but simple to do in C++ like:

struct queue { // a 'struct' is a 'class' where all is 'public' by default
    .
    .
    ssize_t add(int); // in C++ 'this' corresponding to 'self' does not have to be explicitly placed in the params list
};

ssize_t queue::add(int value)
{
    /* Add a element to the queue */
    return ...a ssize_t...;
}

int main(void)
{
    queue * clients = createQueue(5); /* Here i create the queue struct */

    clients->add(5); // '->' rather than '.' because clients is a 'queue*' rather than a 'queue'
}

The corresponding of Python 'self' is named 'this' in C++ and you do not not have to place it explicitly in the parameter list, it is implicit.

Note in C++ there is no garbage collector like in Python, probably createQueue allocate the queue in the heap, in that case if you want to liberate the allocated memory before the end of the execution you have to do delete queue;

And to finish there is an implicit return 0; at the end of main if you do not return by yourself