error template with C linkage

I am using G++ Compiler in LINUX. Why does this section of code causes this error template with C linkage?

Code:

---

template <class T>
class CObjectCreator : public CCacheObjectCreator
{
    T* CreateCacheObject(LPCSTR pszKey, LPCSTR pszExtra) { return new T(pszKey, pszExtra); }
};

---

Code:

---

template <class T>
class CAllocator : public CCacheAllocator
{
public:
    CAllocator(CCache* pCache, LPCSTR pszKey, LPCSTR pszExtra, DWORD dwExpirySecs, T*& pObject) : CCacheAllocator(pCache, pszKey, pszExtra, dwExpirySecs, new CObjectCreator<T>(), (CCacheObject *&)pObject) {}
};

---

Any reason why that code would be within an extern "C" {} brackets?
I would look for that first.

gg

This is an existing source code passed by 3rd party.

Now this file that I am using has headers declared like this

Code:

---

#include "HttpHeaders.h"
#include "List.h"
#include "CriticalSection.h"
#include <map>

---

And once I open HttpHeaders.h...

Code:

---

extern "C"
{
#include "httpd.h"
#include "http_config.h"
#include "http_core.h"
#include "http_log.h"
#include "http_main.h"
#include "http_protocol.h"
#include "http_request.h"
#include "util_script.h"
#include "http_connection.h"
#include "apr_strings.h"
#include "apr_env.h"
#include "apr_atomic.h"
#include "ap_regex.h"
#if !defined(_WINDOWS_)
#include <unistd.h>
#include <ctype.h>
#endif
}

---

Is it this red extern C block creating the problem? I tried removing it but the problem still persists

It could be that this header causes the error.

Normally you define such headers like

Code:

---

#ifdef __cplusplus
extern "C"
{
#endif

#include "httpd.h"
#include "http_config.h"
#include "http_core.h"
#include "http_log.h"
#include "http_main.h"
#include "http_protocol.h"
#include "http_request.h"
#include "util_script.h"
#include "http_connection.h"
#include "apr_strings.h"
#include "apr_env.h"
#include "apr_atomic.h"
#include "ap_regex.h"
#if !defined(_WINDOWS_)
#include <unistd.h>
#include <ctype.h>
#endif
#ifdef __cplusplus
}
#endif

---

That way you can use the header both from C and C++ sources.

All the Apache headers already handle extern "C" {} themselves, so you can remove the unnecessary extern "C" block in HttpHeaders.h.

Look in the other non-Apache headers as well for unnecessary blocks - and for any extern "C" lines without the braces.

Also make sure your template code isn't being compiled as C code, by including it from a file with a ".c" extension.
http://gcc.gnu.org/onlinedocs/gcc/Ov...verall-Options

gg