[Boost-users] [phoenix] compile error using arg1

Subject: [Boost-users] [phoenix] compile error using arg1
From: Paul Heil (paul.heil_at_[hidden])
Date: 2009-02-09 17:13:12

While expanding my horizons to include functional programming, I've run in
to a problem with boost::phoneix lambda functions. I'm trying to use a
for_each() command with an overloaded<< operator, but I can't seem to get
they types right, and I get a compile error:
test.cpp(147) : error C2679: binary '<<' : no operator found which takes a
right-hand operand of type 'const boost::phoenix::actor<Eval>' (or there is
no acceptable conversion)

I've seen example code that's very similiar to this using "cout" instead of
the overloaded << operator  I have, so I tend to think this is possible. My
code is below, can anybody suggest what I could do to fix this?

using namespace boost::phoenix;
using namespace boost::phoenix::arg_names;

class A
{
public:
    friend MSXML2::IXMLDOMNode* operator <<( MSXML2::IXMLDOMNode*
node, const A&
a );

private:
    // ...
};

MSXML2::IXMLDOMNode* operator <<( MSXML2::IXMLDOMNode* node, const A& a )
{
    // Add stuff from A to 'node'
    return node;
}

int main()
{
    MSXML2::IXMLDOMElementPtr pElem;
    // MSXML2 DOM doc creation removed for brevity

    std::list< A > theList;
    // add items to the list...

    // copy items from the list to the XML element
    // This does not compile (C2679)
    std::for_each( theList.begin(), theList.end(), pElem << arg1 );
    return 0;
}

I realize I could write a proxy function like:
void A::Print( MSXML2::IXMLDOMNode* t ) const
{
    t << *this;
};

and use the bind() within the for_each()
std::for_each( theList.begin(), theList.end(), bind( &A::Print, arg1,
pElem ) );

but, I'd like to avoid that if possible.
If anybody can suggest how to get this done, I would appreciate it.

Thanks,
PaulH