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Why doesn't the following work?

template <typename Type>
class A
{
public:
Type data_;
};

template <typename Type>
class B: public A<Type>
{
public:
void set()
{
data_ = 4;
}
};

int main()
{
B<int> b;
b.set();
return 0;
}

If you declare "using A<Type>::data_;" then it works. If you use normal
classes, this works without "using". I don't get it. Tested with
msvc2005 and comeau. Words from the standard?

--
Kalle Rutanen
http://kaba.hilvi.org

On 13/3/06 22:43, in article ,
"Kaba" <> wrote:

> Why doesn't the following work?
>
> template <typename Type>
> class A
> {
> public:
> Type data_;
> };
>
> template <typename Type>
> class B: public A<Type>
> {
> public:
> void set()
> {
> data_ = 4;
> }
> };
>
> int main()
> {
> B<int> b;
> b.set();
> return 0;
> }
>
> If you declare "using A<Type>::data_;" then it works.

But do you understand why that works?

> If you use normal
> classes, this works without "using". I don't get it. Tested with
> msvc2005 and comeau. Words from the standard?

At the risk of doing your homework for you, have a read of

<http://www.parashift.com/c++-faq-lite/templates.html#faq-35.18>

Apart from your example using a member variable and the example in the FAQ
using a member function, they're both remarkably similar!

--
Regards,
Steve

"...which means he created the heaven and the earth... in the DARK! How good
is that?"

> > If you declare "using A<Type>::data_;" then it works.
>
> But do you understand why that works?
>
> > If you use normal
> > classes, this works without "using". I don't get it. Tested with
> > msvc2005 and comeau. Words from the standard?
>
> At the risk of doing your homework for you, have a read of
>
> <http://www.parashift.com/c++-faq-lite/templates.html#faq-35.18>
>
> Apart from your example using a member variable and the example in the FAQ
> using a member function, they're both remarkably similar!

Thank you Steve, this answered my question. No this is not homework, I
just found and switched off the "language extensions" option in visual
studio and got errors I had not seen before

--
Kalle Rutanen
http://kaba.hilvi.org

In article <>,
Kaba <> wrote:
>Why doesn't the following work?
>
>template <typename Type>
>class A
>{
>public:
>Type data_;
>};
>
>template <typename Type>
>class B: public A<Type>
>{
>public:
>void set()
>{
>data_ = 4;
>}
>};
>
>int main()
>{
>B<int> b;
>b.set();
>return 0;
>}
>
>If you declare "using A<Type>::data_;" then it works. If you use normal
>classes, this works without "using". I don't get it. Tested with
>msvc2005 and comeau. Words from the standard?

Have a look at
http://www.comeaucomputing.com/techt...membernotfound
--
Greg Comeau / Celebrating 20 years of Comeauity!
Comeau C/C++ ONLINE ==> http://www.comeaucomputing.com/tryitout
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