When doing interop with a c library, is there a way to automatically generate the fields that are needed for a struct?

For example, when interfacing with the lwan c library:

// lwan.h
struct lwan {
    struct lwan_trie url_map_trie;
    struct lwan_connection *conns;
    struct lwan_strbuf headers;

    struct {
        pthread_barrier_t barrier;
        struct lwan_thread *threads;
        unsigned int max_fd;
        unsigned int count;
    } thread;

    struct lwan_config config;
    struct coro_switcher switcher;

    int main_socket;

    unsigned int n_cpus;
};

module lwan;

extern (C) {
    struct lwan {
      ... // <<< How do I populate this without having to write all the sub structs?
    };
    void lwan_init(lwan* l);
    void lwan_shutdown(lwan* l);
}

import lwan;

void main() {
  lwan l; //This is currently not allocating enough memory
  lwan_init(&l);
  lwan_shutdown(&l);
}

How do I populate the lwan struct without having to write all the sub structs?

I'm thinking that maybe it'll be best to create a wrapper c function that initializes the lwan struct and returns a pointer.

That way I don't have to declare any fields.

extern (C) {
    struct lwan;

    lwan* lwan_make(); //wrapper function (perhaps in wrapper.c)
    void lwan_cleanup(lwan* l); //wrapper function

    void lwan_init(lwan* l);
    void lwan_shutdown(lwan* l);
}

Is there an easier way though?

On Wednesday, 1 July 2020 at 07:26:44 UTC, Anthony wrote:
> When doing interop with a c library, is there a way to automatically generate the fields that are needed for a struct?
[snip]
> Is there an easier way though?

Dstep is probably what you're looking for: https://github.com/jacob-carlborg/dstep

It eats C header files and creates appropriate D files from them.

--
  Simen