减少使用宏的代码重复

Question

I was wondering if someone out there could give me a pointer to reducing duplication when coding.

im required to call a function a number of times to populate a structure, for example:

typedef struct {
    uint16_t u16_a;
    bool b_org;
    char* c_c;
    uint16_t u16_d;

} TEntry;

I need to populate each value of these with a function call, although the return values vary, the same function is used for all. Would a macro be sufficient to create a template in some way, so that the return type would be dependent on the specific parameter ("string")

for example:

Trrelevant::Trrelevant()
{
    TPoint* u_apoint = Insufficient::FindValue("A");
    if (u_bpoint != NULL) {
        int a = u_apoint;
    }

    TPoint* p_apoint = Insufficient::FindValue("borg");
    if (p_bpoint != NULL) {
        bool b = p_bpoint;
    }


    TPoint* p_cpoint = Insufficient::FindValue("C");
    if (etc != NULL) {
        char* c = etc;
    }

    TEct* etc = Insufficient::FindValue("ETC");
    if (etc != ETC) {
        etc = etc;
    }

    TEntry entry = {a,
                    b,
                    c,
                    etc};
}

this code is not compiled or accurate, im just trying to illustrate. Im weak in C++ and new to macros, but would anyone know a way to have a macro solve this?

Thank you for your time

Answer 1

Recently I had the same kind of issue, I'm not sure what kind of source you use for your inputs. Personnaly, I used XML as input. Then I have A Builder class that parses the XML call a factory funciton to build every struct in the c++ using the data from the parser.

I don't think that MACRO or templtes would be of any help (or it would be a bad solution). Note that an external resource (like xml) is nice if ever you want to change without recompiling.

Best

Answer 2

You could do something like this, although I don't know what it really buys you.

#define QuickFindValue(NAME, TYPE, FUNCTION)             \
     TYPE *NAME##Value = Insufficient::FindValue(#NAME); \
     if (NAME##Value == NULL) { FUNCTION; }

You would use it like so:

QuickFindValue(C, TPoint, { 
  char *c = CValue;
  // Do stuff..
});