Question: I use a (C) library with functions taking different parameters but always returning an int greater than zero in case of error:

```
int functionA(int param1, char param2); /* return an error code on failure, 0 otherwise */
int functionB(LIB_BOOLEAN param1);      /* return an error code on failure, 0 otherwise */
// ...

```

I would like to turn them all to be exception ready:

```
if (functionA(param1, param2) > 0)
{ throw std::runtime_error("Method failed"); }

```

Is it possible to write a template to do it once for all method ?

EDIT:
The idea is to avoid checking the result for each functions every time I use them.

Answer: 
Do you mean something like this?

```
template<typename F, typename... Args>
auto my_invoke(F &&f, Args&&... args) {
    if(std::forward<F>(f)(std::forward<Args>(args)...)) {
        throw std::runtime_error("Method failed");
    }
}

```

You can call it as;

```
my_invoke(functionA, 0, 'c');

```
Here’s one approach that doesn’t require changing call sites. Assuming these C functions all have the same convention for return codes, you can write a wrapper that converts the return code to an exception.

```
inline void checked(const char *name, int result) {
    if (result > 0)
        throw std::runtime_error(name);
}

```

Then introduce a preprocessor definition for each function.

```
#define functionA(...) checked("functionA", functionA(__VA_ARGS__))

```

This works because `functionA` will not be expanded within the definition of the `functionA` macro. And variadic macros are standard since C++11.