Dependency injection in C | Together C & C++ | Page 1

Hi all,

I just wanted to know if you ever used some kind of dependency injection in your C projects.

Here some example code to explain in more detail:

#include <stdio.h>

static void some_api_function1(void)
{
  printf("call 1 from API\n");
}

static void some_api_function2(int some_arg)
{
  printf("call 2 from API with arg %d\n", some_arg);
}

static void do_something_v1(void)
{
  printf("call from outside API v1\n");
  some_api_function1();
  some_api_function2(123);
}
typedef void (*f1)(void);
typedef void (*f2)(int);
struct ApiInterface
{
  f1 func1;
  f2 func2;
};

static void do_something_v2(struct ApiInterface *api_interface)
{
  printf("call from outside API v2\n");
  
  // I skipped the check for valid pointer and valid function pointers here
  api_interface->func1();
  api_interface->func2(234);
}

int main(int argc, char **argv)
{
  printf("call from main\n");
  do_something_v1();
  
  ApiInterface api;
  api.func1 = &some_api_function1;
  api.func2 = &some_api_function2;
  do_something_v2(&api);
  return 0;
}

There are 2 ways to call functions: directly(hard coupled) and with dependency injection(loosely coupled).

The idea behind the second option is to easily mock calls to other modules for testing purposes, e.g. a host simulation for devices with hardware usage(I2C, CAN, ...) or for unit testing.

Now my question is if you ever used this mechanism and if yes what was your experience?

#Dependency injection in C