CODEWITHSUNDEEP
c++templates
user1479670
user1479670

Reputation: 1291

How to have template and non-template functions in one file

I have a utility file with a template function and an 'ordinary' function:

#ifndef __UTILS_CPP__
#define __UTILS_CPP__

#include <stdlib.h>

template<typename T> int makeIntN(const T V) { return (int)V;}

int makeIntS(const char *pVal) { return atoi(pVal);}

#endif

These functions are used by two other classes, subA and subB.

SubA.h:

#ifndef __SUBA_H__
#define __SUBA_H__

class SubA {
public:
    SubA() {};
    static int actionN(int i);
    int actionS(const char *p);    
};    
#endif

SubA.cpp:

#include "suba.h"
#include "utils.cpp"

int SubA::actionN(int i) {
    return makeIntN(i);
}

int SubA::actionS(const char *p) {
    return makeIntS(p);
}

SubC.h

#ifndef __SUBC_H__
#define __SUBC_H__

class SubC {
public:
    SubC() {};
    int actionN(float f);
    static int actionS(const char *p);
};    

#endif

SubC.cpp

#include "subc.h"
#include "utils.cpp"

int SubC::actionS(const char *p) {
    return makeIntS(p);
}

int SubC::actionN(float f) {
    return makeIntN(f);
}

In main(), i create instances of these classes and call some of their methods:

cltest.cpp:

#include <stdio.h>
#include "suba.h"
#include "subc.h"

int main() {
    int iResult = -1;

    SubA *psa = new SubA();
    iResult = psa->actionN(17);
    printf("Res A: %d\n", iResult);
    iResult = psa->actionS("17");
    printf("Res A: %d\n", iResult);
    SubC *psc = new SubC();
    iResult = psc->actionN(17.65);
    printf("Res C: %d\n", iResult);

    return iResult;
}

When i compile this like this:g++ clstest.cpp subc.cpp suba.cpp, i obviously get an error because makeIntS() is included each by SubA and SubC.

I tried various ways of #includes and different ways to link, but either makeIntN() is undefined or else makeIntS() is muitply defined.

How can i get this to compile & link without splitting up the utils file into a template part and a non-template part?

Upvotes: 1

Views: 208

Answers (1)

NutCracker
NutCracker

Reputation: 12283

There are 3 ways of having a non-template free function defined in a header file:

  • make a function inline
  • make a function static
  • place function in anonymous namespace

I suggest you to go for making a int makeIntS(const char *pVal); function inline.

Upvotes: 2

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