Simple example of hot loading on mac

Hotload

// made by @filipwanstrom 
// public domain / as is

// The main.c file
#include <stdio.h>
#include <dlfcn.h>
#include <sys/stat.h>
#include <unistd.h>

typedef void (*printfunc)(void);

struct Reloadable {
    char filename[256];
    char symname[256];
    printfunc func;
    void* lib;
    time_t last_modified;
};


time_t get_mod_time(const char* filename)
{
    struct stat file_stat;
    stat(filename, &file_stat);
    return file_stat.st_mtime;
}

void bind_lib(struct Reloadable* r){
    if(r->lib == NULL) {
	void* f = dlopen(r->filename, RTLD_LAZY);
	if(f != NULL) {
	    r->lib = f;
	}
    }else {
	// unload lib first
	dlclose(r->lib);
	void* f = dlopen(r->filename, RTLD_LAZY);
	if(f != NULL) {
	    r->lib = f;
	}
    }
    void *func = dlsym(r->lib, r->symname);
    if (func != NULL) {
	r->func = (printfunc)(func);
    }
    
}

void reload_if_modified(struct Reloadable * reloadable)
{
    time_t n = get_mod_time(reloadable->filename);
    if(n>reloadable->last_modified) {
	reloadable->last_modified = n;
	bind_lib(reloadable);	
    }
}

void printstuff(struct Reloadable * r)
{
    if(r->lib !=NULL && r->func != NULL ) {
	r->func();
    }
    
}

int main (int argc, char **argv)
{
    printf("Loading hotreload host\n");

    struct Reloadable reloadable = {
	"printfuncs.dylib",
	"printstuff", NULL, NULL, 0
    };
    reloadable.last_modified = get_mod_time(reloadable.filename);
    bind_lib(&reloadable);
    while(1) {
	sleep(1);
	printstuff(&reloadable);
	reload_if_modified(&reloadable);

    }

    return 1;
}

// the printfuncs.c file
#include <stdio.h>
void printstuff()
{
    printf("love is everything\n");
}

// the makefile
all: printfuncs hotreload

printfuncs:
	clang -dynamiclib printfuncs.c -o printfuncs.dylib
	
hotreload:
	clang main.c -o hotreload
	
clean:
	rm -rf hotreload printfuncs.dylib