template class does not recnognize template argument

Question

I'm trying to compilate the following code. But, for some reason, the compilation fails. There are many errors, but all of them are related to TYPE in template.

I've examined the code and it looks like. I can not see the problem. It may be a silly mistake, but do not see. Can anyone help?

header file:

namespace rca {

template<class ContainerType>
class SteinerTreeObserver {

public:
    SteinerTreeObserver();
    SteinerTreeObserver(ContainerType & ec, STTree & st, int);

    void set_steiner_tree (STTree &st, int);
    STTree & get_steiner_tree ();

    void set_container (ContainerType & ec);
    ContainerType & get_container ();

    bool add_edge (int, int, int, int);

    void prunning (int, int);

private:
      ContainerType m_ec;
      STTree m_st;  
      DisjointSet2 dset;

};

};

Here is the cpp file:

#include "steiner_tree_observer.h"

using namespace rca;

template<class ContainerType>
SteinerTreeObserver<ContainerType>::SteinerTreeObserver(){}

SteinerTreeObserver<ContainerType>::SteinerTreeObserver(ContainerType & ec,STTree & st,int nodes){}

template<class ContainerType>
void SteinerTreeObserver<ContainerType>::set_steiner_tree (STTree & st, int nodes){}

template<class ContainerType>
STTree & SteinerTreeObserver<ContainerType>::get_steiner_tree ()
{ return m_st;}

void SteinerTreeObserver<ContainerType>::set_container (ContainerType & ec) 
{}

ContainerType & SteinerTreeObserver<ContainerType>::get_container () 
{return m_ec;}

template<class ContainerType>
bool SteinerTreeObserver<ContainerType>::add_edge (int x, 
                                               int y, 
                                               int cost, 
                                               int band_usage)
{ return true;}


template<class ContainerType>
void SteinerTreeObserver<ContainerType>::prunning (int rest, int band)
{}

template class SteinerTreeObserver<EdgeContainer<Comparator, HCell>>;

Output:

steiner_tree_observer.cpp: At global scope:
steiner_tree_observer.cpp:10:21: error: ‘ContainerType’ was not declared in this scope
SteinerTreeObserver<ContainerType>::SteinerTreeObserver(ContainerType & ec,STTree & st,int nodes)
                 ^
steiner_tree_observer.cpp:10:34: error: template argument 1 is invalid
SteinerTreeObserver<ContainerType>::SteinerTreeObserver(ContainerType & ec,STTree & st,int nodes)
                              ^
steiner_tree_observer.cpp:10:56: error: invalid type in declaration before ‘(’ token
SteinerTreeObserver<ContainerType>::SteinerTreeObserver(ContainerType & ec,STTree & st,int nodes)
                                                    ^
steiner_tree_observer.cpp:10:57: error: ‘ContainerType’ was not declared in this scope
SteinerTreeObserver<ContainerType>::SteinerTreeObserver(ContainerType & ec,STTree & st,int nodes)
                                                     ^
steiner_tree_observer.cpp:10:73: error: ‘ec’ was not declared in this scope
SteinerTreeObserver<ContainerType>::SteinerTreeObserver(ContainerType & ec,STTree & st,int nodes)
                                                                         ^
steiner_tree_observer.cpp:10:83: error: expected primary-expression before ‘&’ token
SteinerTreeObserver<ContainerType>::SteinerTreeObserver(ContainerType & ec,STTree & st,int nodes)
                                                                                ^
steiner_tree_observer.cpp:10:85: error: ‘st’ was not declared in this scope
SteinerTreeObserver<ContainerType>::SteinerTreeObserver(ContainerType & ec,STTree & st,int nodes)
                                                                                  ^
steiner_tree_observer.cpp:10:88: error: expected primary-expression before ‘int’
SteinerTreeObserver<ContainerType>::SteinerTreeObserver(ContainerType & ec,STTree & st,int nodes)
                                                                                    ^
steiner_tree_observer.cpp:10:97: error: expression list treated as compound expression in initializer [-fpermissive]
SteinerTreeObserver<ContainerType>::SteinerTreeObserver(ContainerType & ec,STTree & st,int nodes)
                                                                                             ^
steiner_tree_observer.cpp:11:1: error: expected ‘,’ or ‘;’ before ‘{’ token {

steiner_tree_observer.cpp:18:25: error: expected initializer before ‘<’ token
void SteinerTreeObserver<ContainerType>::set_steiner_tree (STTree & st, int nodes)
                       ^
steiner_tree_observer.cpp:25:29: error: expected initializer before ‘<’ token
STTree & SteinerTreeObserver<ContainerType>::get_steiner_tree ()
                           ^
steiner_tree_observer.cpp:30:25: error: expected initializer before ‘<’ token
void SteinerTreeObserver<ContainerType>::set_container (ContainerType & ec) 
                        ^
steiner_tree_observer.cpp:35:1: error: ‘ContainerType’ does not name a type
ContainerType & SteinerTreeObserver<ContainerType>::get_container () 
 ^
steiner_tree_observer.cpp:41:25: error: expected initializer before ‘<’ token
bool SteinerTreeObserver<ContainerType>::add_edge (int x, 
                     ^
steiner_tree_observer.cpp:64:25: error: expected initializer before ‘<’ token
void SteinerTreeObserver<ContainerType>::prunning (int rest, int band)

When you get past the compiling issues, read http://stackoverflow.com/questions/495021/why-can-templates-only-be-implemented-in-the-header-file — chris, Apr 13 '15 at 02:56
Templates can only be defined in the headerfile. http://stackoverflow.com/questions/495021/why-can-templates-only-be-implemented-in-the-header-file?lq=1 — ZachSand, Apr 13 '15 at 03:13
OK. But i've made explicit instantiation in the CPP file. So whats wrong? — Romerito, Apr 13 '15 at 03:16
Hi, I found the problem. :/ I didn't put the template keyword in some methods like: `ContainerType & SteinerTreeObserver::get_container () {return m_ec;}` Thanks!! — Romerito, Apr 13 '15 at 13:06

score 0 · Accepted Answer · answered Apr 13 '15 at 06:56

0

OK. But i've made explicit instantiation in the CPP file. So whats wrong? – Romerito 3 hours ago Where you made a explicit instantiation?

You have to include your cpp in the header (#include "steiner_tree_observer.cpp") and exclude them from the build and remove the "#include "steiner_tree_observer.h"" out of the header. That's cause templates-functions-definitions allways must known when they get instantiated, not like non template-functions/classes.

Btw. explicit instantiation of template-classes just make sense if you export that class. So you can be sure, your linker will take the symbol out of the DLL or Lib you compiled.

answered Apr 13 '15 at 06:56

user4657571

46
2

In the CPP file. `template class SteinerTreeObserver;` – Romerito Apr 13 '15 at 13:03
Your compiler needs the implementation when the header gets include. A forward declaration like that only make sense if you export your class. – user4657571 Apr 14 '15 at 14:56

template class does not recnognize template argument

1 Answers1