template problem

andy andy@softbook.com
Wed Oct 9 11:46:00 GMT 2002


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
>> 
>> 



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