Static and a container templates

[oxforty]

The following produce a LINK2019: Unresolved externals. I was banging
my head a while to figure out why. I have the static member variable
of class A declared in global scope outside of main(), This is
happening only if I have the files in seperate source files. If I cram
them into one, everything is fine and dandy.

Environment: VS2003, WinXP

ServerMap.h
=========

#ifndef SERVERMAP_H
#define SERVERMAP_H

template<class T>

class ServerMap
{
public:
ServerMap();
~ServerMap();
T operator [] (int index);
int size();
private:
enum {SIZE = 100};
T stack[SIZE];
int sz; //current index
};

#endif

ServerMap.cpp
============
#include "servermap.h"

template <class T>
ServerMap<T>::ServerMap()
{
sz = 0;
}

template <class T>
ServerMap<T>::~ServerMap()
{

}

template <class T>
T ServerMap<T>:perator [] (int index)
{
return stack[index];
}

template <class T>
int ServerMap<T>::size()
{
return sz;
}






#include <iostream>
#include <string>
#include "servermap.h"

class A
{

public:
static ServerMap<std::string> mapInfSrv;

};

ServerMap<std::string> A::mapInfSrv;

int main()
{
A::mapInfSrv.size();
return 0;
}


This is what the compile error looks like.
Error produced :

templates.obj : error LNK2019: unresolved external symbol "public: int
__thiscall ServerMap<class std::basic_string<char,struct
std::char_traits<char>,class std::allocator<char> > >::size(void)" (?
size@?$ServerMap@V?$basic_string@DU?$char_traits@D@std@@V?
$allocator@D@2@@std@@@@QAEHXZ) referenced in function _main
templates.obj : error LNK2019: unresolved external symbol "public:
__thiscall ServerMap<class std::basic_string<char,struct
std::char_traits<char>,class std::allocator<char> > >::ServerMap<class
std::basic_string<char,struct std::char_traits<char>,class
std::allocator<char> > >(void)" (??0?$ServerMap@V?$basic_string@DU?
$char_traits@D@std@@V?$allocator@D@2@@std@@@@QAE@XZ) referenced in
function _$E1
templates.obj : error LNK2019: unresolved external symbol "public:
__thiscall ServerMap<class std::basic_string<char,struct

::~ServerMap<class std::basic_string<char,struct

std::char_traits<char>,class std::allocator<char> > >(void)" (??1?
$ServerMap@V?$basic_string@DU?$char_traits@D@std@@V?
$allocator@D@2@@std@@@@QAE@XZ) referenced in function _$E2
Debug/templates.exe : fatal error LNK1120: 3 unresolved externals


Any help is appreciated

 

[Alf P. Steinbach]

* oxforty:

The following produce a LINK2019: Unresolved externals. I was banging
my head a while to figure out why. I have the static member variable
of class A declared in global scope outside of main(), This is
happening only if I have the files in seperate source files. If I cram
them into one, everything is fine and dandy.

<url: http://www.parashift.com/c++-faq-lite/templates.html#faq-35.12>

Cheers, & hth.,

- Alf