Compilation error of variadic template (C++0x)

From:

Adam Badura <abadura@o2.pl>

Newsgroups:

comp.lang.c++.moderated

Date:

Wed, 7 Nov 2007 22:27:48 CST

Message-ID:

<1194460627.291084.132620@k79g2000hse.googlegroups.com>

    I am using GCC 3.4.4 (Cygwin) and I have variadicg++ 4.1.1 instaled
on this.
    Lets take a look at the code (I wrote to make myself more familiar
with variadic templates) in file named temp.cpp:

template<typename... Values>
struct list;

template<>
struct list<> {
    typedef list<> tail;
};

template<typename Head, typename... Tail>
struct list<Head, Tail...> {
    typedef Head head;
    typedef list<Tail...> tail;
};

template<typename... Lists>
struct join;

template<typename... ListElements>
struct join<list<ListElements...> > {
    typedef list<ListElements...> type;
};

template<typename... ListElements, typename... ListElements2,
typename... Lists>
struct join<list<ListElements...>, list<ListElements2...>, Lists...> {
    typedef join<list<ListElements..., ListElements2...>, Lists...>::type
type;
};

    After compiling it I get following error:

temp.cpp:26: error: type 'join<list<ListElements ...,
ListElements2 ...>, Lists ...>' is not derived from type
'join<list<ListElements ...>, list<Tail ...>, Lists ...>'
temp.cpp:26: error: expected ';' before 'type'

    I don't understand the error. The reason of it.
    All I wanted to express with "join" is that "join" of a single list
is that list and "join" of two lists and perhaps something more is
"join" of those two lists joined and the rest.
    What is wrong?

    Adam Badura

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