template problem

template problem

[andy]

I'm having trouble compiling the following in gcc3.2:

template <class FilterClass, class DataClass = CDataCOLORREF>

class C2PassScale 
{
public:
    typedef DataClass::_DataType _DataType; //ERROR -see below
    typedef DataClass::_RowType _RowType;
    ....


//class CDataCOLORREF is declared below in the same file
class CDataCOLORREF {
public:
  typedef unsigned long_DataType;
....

ERROR above reads:
"ISO C++ forbids declaration of _DataType with no type"

Now,  if I understand the code correctly, the _DataType variable of the
C2PassScale class is typedef'ed to be the same as _DataType variable of the
the CDataCOLORREF class, i.e, long.
It looks like gcc cannot figure out what type the _DataType variable of
C2PassScale class needs to be.
I wonder if anyone can help finding a workaround or maybe a compile option I
need to turn on

Thanks in advance
Andy

Re: template problem

[Eljay Love-Jensen]

Hi Andy,

Try this...

class C2PassScale
{
public:
     typedef typename DataClass::_DataType _DataType;
     typedef typename DataClass::_RowType _RowType;
     ....

The problem should go away.

--Eljay

Re: template problem

[andy]

Thanks to all who responded.
typename did indeed fix it.

Regards
Andy


On 10/9/02 10:12 AM, "Moore, Mathew L"  wrote:

> The compiler doesn't realize that _DataType is a typename within DataClass
> (it could, after all, be a function or variable), so you have to explicitly
> tell it.  This is accomplished using the "typename" keyword:
> 
> template <class FilterClass, class DataClass>
> class P2PassScale
> {
> public:
> typedef typename DataClass::_DataType _DataType;
> ...
> 
> 
> 
>> -----Original Message-----
>> From: andy [mailto:andy@softbook.com]
>> Sent: Wednesday, October 09, 2002 12:34
>> To: gcc-help@gcc.gnu.org
>> Subject: template problem
>> 
>> 
>> I'm having trouble compiling the following in gcc3.2:
>> 
>> template <class FilterClass, class DataClass = CDataCOLORREF>
>> 
>> class C2PassScale
>> {
>> public:
>>     typedef DataClass::_DataType _DataType; //ERROR -see below
>>     typedef DataClass::_RowType _RowType;
>>     ....
>> 
>> 
>> //class CDataCOLORREF is declared below in the same file
>> class CDataCOLORREF {
>> public:
>>   typedef unsigned long_DataType;
>> ....
>> 
>> ERROR above reads:
>> "ISO C++ forbids declaration of _DataType with no type"
>> 
>> Now,  if I understand the code correctly, the _DataType
>> variable of the
>> C2PassScale class is typedef'ed to be the same as _DataType
>> variable of the
>> the CDataCOLORREF class, i.e, long.
>> It looks like gcc cannot figure out what type the _DataType
>> variable of
>> C2PassScale class needs to be.
>> I wonder if anyone can help finding a workaround or maybe a
>> compile option I
>> need to turn on
>> 
>> Thanks in advance
>> Andy
>> 
>> 

Template problem

[jpyubero]

Hi,

        I compiled the program Xvision perfetly under RedHat, but now I`ve
install Mandrake and It's no possible.
When I typing make the exit is:

 make

g++  -g -I- -I. -I~/xvision/include -I~/xvision -w -c prueba.cxx -o prueba.o
In file included from Video.hh:41,
                 from CWindow.hh:34,
                 from BasicFeature.hh:37,
                 from FTypes.hh:32,
                 from Line.hh:33,
                 from prueba.cxx:5:
Image.hh:31: return type specified for `operator XVImage<float>'
make: *** [prueba.o] Error 1


The file Image.hh is:

    #ifndef Image_hh
#define Image_hh

#include "Tracker.hh"
#include "XVImage.hh"

class Image : public XVImage<int>
{
  public:

  Image (int ncols_in = 0, int nrows_in = 0)
    : XVImage<int>(nrows_in, ncols_in)
  {}

  Image (XVImage<int>& im)
    : XVImage<int>(im)
  {}


#if (XV_OS == XV_IRIX)
  operator XVImage<float>() {
    float* floatData = new float[storesize];

    for (int i = 0; i < storesize; i++)
      floatData[i] = (float)image[i];
    XVImage<float> newImage(nrows, ncols, floatData
    delete floatData;
    return newImage;
  }
#else
  XVImage<float> operator XVImage<float>()
{                                                          //Number of line 31
    float* floatData = new float[storesize];

    for (int i = 0; i < storesize; i++)
      floatData[i] = (float)image[i];
    XVImage<float> newImage(nrows, ncols, floatData
    delete floatData;
    return newImage;
  }
#endif

};

#endif Image_hh




And the lines where is implemented in another file is:

template <class T> XVImage<T> &operator >>(const ColVector &x,XVImage<T> &y);
template <class T> XVImage<T> &operator >>(const RowVector &x,XVImage<T> &y);

Can anyboby help me?


Sorry for my english

Thanks.

Re: Template problem

[Alexandre Oliva]

On Apr  2, 2001, jpyubero <gva09@elai.upm.es> wrote:

> Image.hh:31: return type specified for `operator XVImage<float>'

>   XVImage<float> operator XVImage<float>()

So, the code is ill-formed, and GCC tells you what the problem is.

-- 
Alexandre Oliva   Enjoy Guarana', see http://www.ic.unicamp.br/~oliva/
Red Hat GCC Developer                  aoliva@{cygnus.com, redhat.com}
CS PhD student at IC-Unicamp        oliva@{lsd.ic.unicamp.br, gnu.org}
Free Software Evangelist    *Please* write to mailing lists, not to me

Template problem

[Michael Ben-Gershon]

I am having problems with templates on gcc-2.95.2. I am sure
that the code worked on some earlier version of gcc, but I
don't recall exactly which version it was.

I have a Range class defined as:

template <class T, T lower, T upper>
class Range
{
...
};

It has a number of non-member functions defined for the various
operators. In particular, it has the following defined:

template<class T, T lower, T upper>
ostream&
operator<< (ostream& out_stream, const Range<T, lower, upper>& the_value);

In the main program, I have

int main()
{
  Range<int, -5, 5> f = -5;

  cout << endl;
  
  cout << "Number is: " << f << endl;
...

When compiling (all the code, including the implementation of the 
function above, is in one file) I get the following error:

test_range.cc: In function `int main()':
test_range.cc:18: no match for `ostream & << Range<int,-5,5> &'
/usr/local/lib/gcc-lib/i686-pc-linux-gnu/2.95.2/../../../../include/g++-3/iostream.h:77:
candidates are: class ostream & ostream::operator <<(char)
/usr/local/lib/gcc-lib/i686-pc-linux-gnu/2.95.2/../../../../include/g++-3/iostream.h:78:                
class ostream & ostream::operator <<(unsigned char)
/usr/local/lib/gcc-lib/i686-pc-linux-gnu/2.95.2/../../../../include/g++-3/iostream.h:79:                
class ostream & ostream::operator 

etc, etc, etc ...

The strange thing is that I have a derived class, which behaves fine!
It is defined as:

template<int lowest, int highest>
class Floor_Number : public Range<int, lowest, highest>
{
...
};

With the ostream stuff defined as:

template<int lowest, int highest>
ostream&
operator<< (ostream& out_stream, const Floor_Number<lowest, highest>&
the_value);

and is used in the test program as:

Floor_Number<-3, 10> Ff = -5;

cout << "The floor is: " << Ff << endl;

What is wrong with the Range stuff? If it is wrong, how is it that the derived
class Floor_Number is OK?

Thanks,

Michael Ben-Gershon
mybg@netvision.net.il

Template problem

[Michael Ben-Gershon]

I am having problems with templates on gcc-2.95.2. I am sure
that the code worked on some earlier version of gcc, but I
don't recall exactly which version it was.

I have a Range class defined as:

template <class T, T lower, T upper>
class Range
{
...
};

It has a number of non-member functions defined for the various
operators. In particular, it has the following defined:

template<class T, T lower, T upper>
ostream&
operator<< (ostream& out_stream, const Range<T, lower, upper>& the_value);

In the main program, I have

int main()
{
  Range<int, -5, 5> f = -5;

  cout << endl;
  
  cout << "Number is: " << f << endl;
...

When compiling (all the code, including the implementation of the 
function above, is in one file) I get the following error:

test_range.cc: In function `int main()':
test_range.cc:18: no match for `ostream & << Range<int,-5,5> &'
/usr/local/lib/gcc-lib/i686-pc-linux-gnu/2.95.2/../../../../include/g++-3/iostream.h:77:
candidates are: class ostream & ostream::operator <<(char)
/usr/local/lib/gcc-lib/i686-pc-linux-gnu/2.95.2/../../../../include/g++-3/iostream.h:78:                
class ostream & ostream::operator <<(unsigned char)
/usr/local/lib/gcc-lib/i686-pc-linux-gnu/2.95.2/../../../../include/g++-3/iostream.h:79:                
class ostream & ostream::operator 

etc, etc, etc ...

The strange thing is that I have a derived class, which behaves fine!
It is defined as:

template<int lowest, int highest>
class Floor_Number : public Range<int, lowest, highest>
{
...
};

With the ostream stuff defined as:

template<int lowest, int highest>
ostream&
operator<< (ostream& out_stream, const Floor_Number<lowest, highest>&
the_value);

and is used in the test program as:

Floor_Number<-3, 10> Ff = -5;

cout << "The floor is: " << Ff << endl;

What is wrong with the Range stuff? If it is wrong, how is it that the derived
class Floor_Number is OK?

Thanks,

Michael Ben-Gershon
mybg@netvision.net.il

Re: Template problem

[Alex Vinokur]

In article <38691EC2.598C836F@netvision.net.il>,
  Michael Ben-Gershon <mybg@netvision.net.il> wrote:
> I am having problems with templates on gcc-2.95.2. I am sure
> that the code worked on some earlier version of gcc, but I
> don't recall exactly which version it was.
>
> I have a Range class defined as:
>
> template <class T, T lower, T upper>
> class Range
> {
> ...
> };
>
> It has a number of non-member functions defined for the various
> operators. In particular, it has the following defined:
>
> template<class T, T lower, T upper>
> ostream&
> operator<< (ostream& out_stream, const Range<T, lower, upper>&
the_value);
>
> In the main program, I have
>
> int main()
> {
>   Range<int, -5, 5> f = -5;
>
>   cout << endl;
>
>   cout << "Number is: " << f << endl;
> ...
>
> When compiling (all the code, including the implementation of the
> function above, is in one file) I get the following error:
>
> test_range.cc: In function `int main()':
> test_range.cc:18: no match for `ostream & << Range<int,-5,5> &'
>
/usr/local/lib/gcc-lib/i686-pc-linux-gnu/2.95.2/../../../../include/g++-3/iostream.h:77:
> candidates are: class ostream & ostream::operator <<(char)
>
/usr/local/lib/gcc-lib/i686-pc-linux-gnu/2.95.2/../../../../include/g++-3/iostream.h:78:
> class ostream & ostream::operator <<(unsigned char)
>
/usr/local/lib/gcc-lib/i686-pc-linux-gnu/2.95.2/../../../../include/g++-3/iostream.h:79:
> class ostream & ostream::operator
>
> etc, etc, etc ...
>
> The strange thing is that I have a derived class, which behaves fine!
> It is defined as:
>
> template<int lowest, int highest>
> class Floor_Number : public Range<int, lowest, highest>
> {
> ...
> };
>
> With the ostream stuff defined as:
>
> template<int lowest, int highest>
> ostream&
> operator<< (ostream& out_stream, const Floor_Number<lowest, highest>&
> the_value);
>
> and is used in the test program as:
>
> Floor_Number<-3, 10> Ff = -5;
>
> cout << "The floor is: " << Ff << endl;
>
> What is wrong with the Range stuff? If it is wrong, how is it that the
derived
> class Floor_Number is OK?
>
> Thanks,
>
> Michael Ben-Gershon
> mybg@netvision.net.il
>


The following code has no problem when
        compiling on g++ (egcs-2.91.5).


        Alex

//#########################################################
//------------------- C++ code : BEGIN -------------------

#include <iostream>

//-----------------------------------
template <class T, T lower, T upper>
class Range
{
        public :
                T       value_;
                Range (const T& value_i)
                {
                        value_ = value_i;
                }
};

//-----------------------------------
template<class T, T lower, T upper>
ostream&
operator<< (ostream& out_stream, const Range<T, lower, upper>&
the_value)
{
        return out_stream << the_value.value_;
}

//-----------------------------------
int main()
{
  Range<int, -3, 5> f (-2);

  cout << endl;

  cout << "Number is: " << f << endl;

  return 0;
}


//------------------- C++ code : END ----------------------





//#########################################################
//------------------- Running Results : BEGIN -------------

Number is: -2

//------------------- Running Results : END ---------------




//#########################################################
//------------------- Environment -------------------------

g++ -v     : gcc version egcs-2.91.57 19980901
             (egcs-1.1 release)

uname -sr  : SunOS 5.6

//---------------------------------------------------------



//#########################################################



Sent via Deja.com http://www.deja.com/
Before you buy.

Re: Template problem

[Alex Vinokur]

In article <38691EC2.598C836F@netvision.net.il>,
  Michael Ben-Gershon <mybg@netvision.net.il> wrote:
> I am having problems with templates on gcc-2.95.2. I am sure
> that the code worked on some earlier version of gcc, but I
> don't recall exactly which version it was.
>
> I have a Range class defined as:
>
> template <class T, T lower, T upper>
> class Range
> {
> ...
> };
>
> It has a number of non-member functions defined for the various
> operators. In particular, it has the following defined:
>
> template<class T, T lower, T upper>
> ostream&
> operator<< (ostream& out_stream, const Range<T, lower, upper>&
the_value);
>
> In the main program, I have
>
> int main()
> {
>   Range<int, -5, 5> f = -5;
>
>   cout << endl;
>
>   cout << "Number is: " << f << endl;
> ...
>
> When compiling (all the code, including the implementation of the
> function above, is in one file) I get the following error:
>
> test_range.cc: In function `int main()':
> test_range.cc:18: no match for `ostream & << Range<int,-5,5> &'
>
/usr/local/lib/gcc-lib/i686-pc-linux-gnu/2.95.2/../../../../include/g++-3/iostream.h:77:
> candidates are: class ostream & ostream::operator <<(char)
>
/usr/local/lib/gcc-lib/i686-pc-linux-gnu/2.95.2/../../../../include/g++-3/iostream.h:78:
> class ostream & ostream::operator <<(unsigned char)
>
/usr/local/lib/gcc-lib/i686-pc-linux-gnu/2.95.2/../../../../include/g++-3/iostream.h:79:
> class ostream & ostream::operator
>
> etc, etc, etc ...
>
> The strange thing is that I have a derived class, which behaves fine!
> It is defined as:
>
> template<int lowest, int highest>
> class Floor_Number : public Range<int, lowest, highest>
> {
> ...
> };
>
> With the ostream stuff defined as:
>
> template<int lowest, int highest>
> ostream&
> operator<< (ostream& out_stream, const Floor_Number<lowest, highest>&
> the_value);
>
> and is used in the test program as:
>
> Floor_Number<-3, 10> Ff = -5;
>
> cout << "The floor is: " << Ff << endl;
>
> What is wrong with the Range stuff? If it is wrong, how is it that the
derived
> class Floor_Number is OK?
>
> Thanks,
>
> Michael Ben-Gershon
> mybg@netvision.net.il
>


The following code has no problem when
        compiling on g++ (egcs-2.91.5).


        Alex

//#########################################################
//------------------- C++ code : BEGIN -------------------

#include <iostream>

//-----------------------------------
template <class T, T lower, T upper>
class Range
{
        public :
                T       value_;
                Range (const T& value_i)
                {
                        value_ = value_i;
                }
};

//-----------------------------------
template<class T, T lower, T upper>
ostream&
operator<< (ostream& out_stream, const Range<T, lower, upper>&
the_value)
{
        return out_stream << the_value.value_;
}

//-----------------------------------
int main()
{
  Range<int, -3, 5> f (-2);

  cout << endl;

  cout << "Number is: " << f << endl;

  return 0;
}


//------------------- C++ code : END ----------------------





//#########################################################
//------------------- Running Results : BEGIN -------------

Number is: -2

//------------------- Running Results : END ---------------




//#########################################################
//------------------- Environment -------------------------

g++ -v     : gcc version egcs-2.91.57 19980901
             (egcs-1.1 release)

uname -sr  : SunOS 5.6

//---------------------------------------------------------



//#########################################################



Sent via Deja.com http://www.deja.com/
Before you buy.