C++ code generation for repeated task

Question

I have something like below which will get repeated many times based on the function that get called

for eg

  acceptfunction()
  {
       inserter["quantity"] = sdd.getfloat(quantity);
       inserter["prodtype"]  = sdd.getstring(prodtype);
         :
         :
       so on 
   }

Like accept above there are 20 more functions(reject,cancel etc) which will do the similar thing.But the parameteres they insert can differ based on function called.

How can I automate this kind of code.So that I dont need to write new function from scratch.Basically what I need is if i provide parametres like ("quantity",prodtype) through some text file or xml, it should generate the required function with the input parametres.

Is this task can be handled through C++ tempalte Meta programming or someother code generation tool will help me to do this?

Answer 1

It's ugly, but you can use a preprocessor macro:

#define FUNCTION_MACRO(NAME, ATTRIB1, ATTRIB2)\
void NAME()\
{\
    inserter[#ATTRIB1] = sdd.getfloat(ATTRIB1);\
    inserter[#ATTRIB2]  = sdd.getstring(ATTRIB2);\
}

And then to create a function you just need to do:

FUNCTION_MACRO(accept_function, quantity, prodtype)

Answer 2

Well, when it comes down do it, you almost certainly could but it would require implementing an XML or text parser in TMP. Would be quite a feat.

That's not how things would normally be done, but you've not specified enough details to go into it further.

Answer 3

Macros are generally to be avoided, but this is a case where they are still useful. Something like

#define GET_FUNCTION(type, name)                    \
    do                                              \
    {                                               \
        inserter[#name] = sdd.get ## type(name);    \
    }                                               \
    while (0)

will let you say

void acceptfunction()
{
    GET_FUNCTION(float, quantity);
    GET_FUNCTION(string, prodtype);
    // etc...
}

(The reason for the odd do-while construct is to guarantee that the result is a single statement.)

Define different macros for rejectfunction(), etc.