template(s) declaration with GCC3.2-7

template(s) declaration with GCC3.2-7

[Rade Trimceski]

Hey guys (and girls if there are any) :)

I'm trying to compile code that was written a while ago, and compiled
just fine with gcc 2.96. GCC 3.2-7 doesn't like it at all. Here's the
code as I extracted it from the header file:

[rtrimces@Vaio tests]#cat template_test.cpp
#include <list>

template <class _Tp>
class LsList : public list<_Tp> {
public:
	typedef list<_Tp> baseList;
	LsList() : baseList() {}
	LsList(const _Tp& x) : baseList(1, x) {}
	void eraseAll() {
		baseList::erase(begin(), end());
	}
	LsList<_Tp>& operator= (const LsList<_Tp> & x) {
		return (LsList<_Tp> &)baseList::operator= (x);
	}
};

When trying to compile I get the following errors:
[rtrimces@Vaio tests]# g++ -o template.o template_test.cpp
template_test.cpp:4: parse error before `<' token
template_test.cpp:7: ISO C++ forbids declaration of `LsList' with no
type
template_test.cpp: In function `int LsList()':
template_test.cpp:7: `int LsList()' redeclared as different kind of
symbol
template_test.cpp:4: previous declaration of `template<class _Tp> class
LsList'
template_test.cpp:4: previous non-function declaration `template<class
_Tp>
   class LsList'
template_test.cpp:7: conflicts with function declaration `int LsList()'
template_test.cpp:7: only constructors take base initializers
template_test.cpp:7: confused by earlier errors, bailing out



Can someone tell me what has changed with the compiler and why this code
doesn't compile anymore? Even better answer would be how should I write
this code in order to make it compile with gcc 3.2.

Thanks a lot!
Rade
P.S.
In case you are wondering:
[rtrimces@Vaio tests]# g++ --version
g++ (GCC) 3.2 20020903 (Red Hat Linux 8.0 3.2-7)

Re: template(s) declaration with GCC3.2-7

[John Love-Jensen]

Have you tried...

Line 4: class LsList : public std::list<_Tp> {

...?

--Eljay

More template(s) errors with GCC3.2-7

[Rade Trimceski]

Can someone demystify this error for me?

It comes out of a header file, and this did compile with gcc 2.96.

typedef hash_map<int, Neighbor_Entry *> Neighbors_Hash;

the compilation error is:

In file included from diffusion3/apps/gear/geo-routing.cc:11:
diffusion3/apps/gear/geo-routing.hh:187: syntax error before `;' token


Any ideas why I get the syntax error, and what it really means?

Thanks a lot!
Rade

Re: More template(s) errors with GCC3.2-7

[Oscar Fuentes]

Rade Trimceski <rtrimces@mtu.edu> writes:

> Can someone demystify this error for me?
>
> It comes out of a header file, and this did compile with gcc 2.96.
>
> typedef hash_map<int, Neighbor_Entry *> Neighbors_Hash;
>
> the compilation error is:
>
> In file included from diffusion3/apps/gear/geo-routing.cc:11:
> diffusion3/apps/gear/geo-routing.hh:187: syntax error before `;' token
>
>
> Any ideas why I get the syntax error, and what it really means?

Well, the error message is not a great help on this case. What really
happens is that 'hash_map' is an unknown template for the compiler.

GCC 3.x comes with a new Standard C++ Library implementation, which is
far more conformant than the previous one. All standard C++ library
names are on namespace 'std'.

For this specific case, 'hash_map' is not a standard C++ library
template. However, the GNU implementors added it for supporting old
code (and as a nice extension, I guess). It's on namespace __gnu_cxx,
implemented on <ext/hash_map>.

I think this issues are explained on some README on the GCC
distribution or on the website. The 'std' namespace thing is something
every C++ developer should know since a long time ago, though.

-- 
Oscar

please unsubscribe

[claudio]

RE: template(s) declaration with GCC3.2-7

[Rupert Wood]

Rade Trimceski wrote: 

> I'm trying to compile code that was written a while ago, and
> compiled just fine with gcc 2.96. GCC 3.2-7 doesn't like it at all.
:
> #include <list>
> 
> template <class _Tp>
> class LsList : public list<_Tp> {

The newer C++ standards place the STL classes, list et al, inside the 'std'
namespace.

This means you can either address it in full:

    class LsList : public std::list<_Tp> {

or import the elements you need from the std namespace:

    #include <list>
    using std::list;

or import the std namespace wholesale:

    #include <list>
    using namespace std;

In header files, I prefer the first since you're not polluting the global
namespace of source files that include the header. In C++ sources (.cpp,
.cc, etc.) I prefer the second form since it's more precise but lots just
use the third because it's simplest. But this is just a matter of style so
use whichever suits you.

Hope that helps,
Rup.