Inline return to original caller - c++

Question

I have a C++ wrapper to wrap a library for C. The wrapper frequently performs a variable check. I would like to break this down into an inline function call, but I would like the inline function to return to the original caller if the check fails.
For the sake of simplicity, we'll call the library I wrapped libraryA and we'll call the library's object objectA.
Here's what I'm doing:
#define LIBRARY_A_NULL_PARAMETER -1
#define LIBRARY_A_CAST_FAIL -2
signed int wrapper_doSomething(void *ptrVariable){
libraryA::objectA *objA;
/* variable checks */
if(!ptrVariable){
return LIBRARY_A_NULL_PARAMETER;
}
try{
objA = (libraryA::objectA *)ptrVariable;
}catch(...){
return LIBRARY_A_CAST_FAIL;
}
/* perform the rest of the function */
}
Because this check is performed in nearly every function, I'd like to simplify this to something like:
#define LIBRARY_A_NULL_PARAMETER -1
#define LIBRARY_A_CAST_FAIL -2
inline signed int checkVariable(void *ptrVariable, libraryA::objectA **assignTo){
if(!ptrVariable){
return LIBRARY_A_NULL_PARAMETER;
}
try{
*assignTo = (libraryA::objectA *)ptrVariable;
return 1; // success
}catch(...){
return LIBRARY_A_CAST_FAIL;
}
}
signed int wrapper_doSomething(void *ptrVariable){
libraryA::objectA *objA;
/* variable checks */
checkVariable(ptrVariable, &objA);
/* perform the rest of the function */
}
I'd like the checkVariable() function to return back to the original caller if the check fails.
Because all error codes are negative numbers, I can of course say:
int response = checkVariable(ptrVariable, &objA);
if(response < 0){
return response;
}
This would handle the situation, but I would like to remove the if-statement, if possible, and thus reduce the variable check to exactly one line. Is this achievable?
I plan on looking into macros, but I have not used macros before, so I'm not sure if they could accomplish this either.
EDIT:
Per Anton's answer, would a macro definition like this suffice:
#define CHECK_VARIABLE(ptrVariable, objA) \
{\
if(!ptrVariable) return LIBRARY_A_NULL_PARAMETER;\
try{\
*objA = (libraryA::objectA *)ptrVariable;\
}catch(...){\
return LIBRARY_A_CAST_FAIL;\
}\
}
I would then call it as:
CHECK_VARIABLE(ptrVariable, &objA);

Answer 1

Without exceptions you have to use macros. Given you have checkVariable() function, the macro can look like this:
#define CHECK_VARIABLE(ptrVariable, objA) \
{\
int response = checkVariable((ptrVariable), &(objA));\
if (response < 0)\
return response;\
}

Answer 2

As you are using exceptions already, you can use them for that purpose, too:
inline signed int checkVariable(void *ptrVariable, libraryA::objectA **assignTo) {
if (!ptrVariable) {
throw LIBRARY_A_NULL_PARAMETER;
}
try {
*assignTo = (libraryA::objectA *)ptrVariable;
return 1; // success
} catch(...) {
throw LIBRARY_A_CAST_FAIL;
}
}
You can write the wrapper_doSomething function exactly as desired but the caller of that function has to catch the exception that is passed along.