template compilation problem

[Mark P]

I'm having a problem compiling some template code. Here's a seemingly
useless block of code which I've stripped down to illustrate my problem.
Why is the second call to a.foo not accepted by the compiler? Advice
and suggestions are welcomed.

Thanks,
Mark

#include <iterator>
#include <list>

using namespace std;

template <typename T>
struct A
{
template <typename OutIter>
void foo (OutIter& oi);
};


template <typename T>
template <typename OutIter>
void A<T>::foo (OutIter& oi)
{}

int main ()
{
A<int> a;
list<int> output;

// this is fine:
back_insert_iterator<list<int> > bii = back_inserter(output);
a.foo(bii);

// this is not:
a.foo(back_inserter(output));
}

 

[Pete C]

struct A
{
template <typename OutIter>
void foo (OutIter& oi);
};
<snip>
a.foo(back_inserter(output));

The error has nothing to do with templates. The problem is that you
can't bind a temporary to a non-const reference (as I imagine your
compiler is telling you).
For example:
int &a = int(5);
is not valid, but
const int &a = int(5);
is OK. Your argument to foo is a non-const reference. Either pass it by
value, or do what you have done above.

 

[Mark P]

I'm having a problem compiling some template code. Here's a seemingly
useless block of code which I've stripped down to illustrate my problem.
Why is the second call to a.foo not accepted by the compiler? Advice
and suggestions are welcomed.

Hmm, I think I've figured this one out. The compiler doesn't like my
passing a temporary by non-constant reference. As you might guess, the
argument here is an Output Iterator and it suits me fine to modify and
discard the temporary, but I guess rules are rules.

Thanks,
Mark

 

[Diego Martins]

The error has nothing to do with templates. The problem is that you
can't bind a temporary to a non-const reference (as I imagine your
compiler is telling you).
For example:
int &a = int(5);
is not valid, but
const int &a = int(5);
is OK. Your argument to foo is a non-const reference. Either pass it by
value, or do what you have done above.

is this related to the proposed C++ extension && on arguments?