🚀 go-pugleaf

"Mike K" <mkipper@rogers.com> wrote:

>Hi,
>
>As an example, can someone please tell me why this won't work?
>
>IN HEADER.CPP
>------------------------------------------------------------
>#include "header.h"
>template <typename X, typename Y>
>A<X,Y>::A(void)
>{}
>
>template <typename X, typename Y>
>A<X,Y>::~A(void)
>{}
>------------------------------------------------------------
>
>IN HEADER.H
>------------------------------------------------------------
>#ifndef __HEADER_H_INCLUDED__
>#define __HEADER_H_INCLUDED__
>
>template <typename X, typename Y>
>class A
>{
>public:
>    A();
>    ~A();
>};
>
>#endif /* !defined(__HEADER_H_INCLUDED__) */
>------------------------------------------------------------
>
>IN MAIN.CPP
>------------------------------------------------------------
>#include "header.h"
>int main(void)
>{
>    A<char, int> b;
>    return 0;
>}
>------------------------------------------------------------
>
>
>ERROR MESSAGES
>------------------------------------------------------------
>Compiling...
>header.cpp
>Linking...
>main.obj : error LNK2001: unresolved external symbol "public: __thiscall
>A<char,int>::~A<char,int>(void)" (??1?$A@DH@@QAE@XZ)
>main.obj : error LNK2001: unresolved external symbol "public: __thiscall
>A<char,int>::A<char,int>(void)" (??0?$A@DH@@QAE@XZ)
>Debug/DELETE ME.exe : fatal error LNK1120: 2 unresolved externals
>Error executing link.exe.
>
>DELETE ME.exe - 3 error(s), 0 warning(s)
>------------------------------------------------------------
>
>
>Thanks for your help!
>
>Mike

When the compiler compiles header.cpp it doesn't know which version of A in
create. When it compiles mai.cpp it doesn't know how to instance A. The export
keyword is supposed to handle this, but almost no compilers support it in a
usable manner.



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