In the following:

#include <set>

typename<class T>
class C {
public:
    typedef set<T>   Set;
    typedef Set::iterator  Iterator; // is this wrong?
    typedef typename Set::iterator Iterator2; // is this right?
};

isn't Set::iterator a dependent name which requires the use of typename,
since it is the same as set<T>::iterator?

Sun C++ 5.0 accepts this without using typename.

--
Jon Biggar
Floorboard Software
jon@floorboard.com
jon@biggar.org


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Jonathan Biggar <jon@floorboard.com> writes:

>In the following:

>#include <set>

>typename<class T>
>class C {
>public:
>    typedef set<T>   Set;
>    typedef Set::iterator  Iterator; // is this wrong?
>    typedef typename Set::iterator Iterator2; // is this right?
>};

>isn't Set::iterator a dependent name which requires the use of typename,
>since it is the same as set<T>::iterator?

Yes. In fact, you need typename on the first typedef as well.

>Sun C++ 5.0 accepts this without using typename.

As explained in the documentation that comes with the compiler,
Sun C++ 5.0 recognizes the keyword "typename" but does not
enforce its use.

Speaking more generally:

The purpose of adding typename to the standard was only to allow a
compiler to diagnose some errors in a template definition without
needing to wait for an instantiation. (Without knowing which names
are types, the compiler cannot begin to parse a template definition.)
Typename does not address any template correctness or ambiguity issue,
since a compiler can choose to wait until instantiation time
before detecting any errors. At instantiation time, the meaning
of every declared name is known.

--
Steve Clamage, stephen.clamage@sun.com
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