[Boost-users] Boost.Signals doc_view example application question?

From: Allen Gooch (mojocode_at_[hidden])
Date: 2006-08-02 19:20:38

I have a quick question regarding connecting a bound member function.  In
the doc_view example application signals are defined as requiring a function
taking a bool and returning nothing.

class Document
{
public:
    typedef boost::signal< void (bool) >  signal_t;
    // ...

    void append(const char* s)
    {
        m_text += s;
        m_sig(true);
    }
    // ...
};

The View abstract base class requires concrete bases to provide a concrete
implementation of the refresh() member function matching the slot signature
required.

class View
{
public:
    virtual void refresh(bool) const = 0;
    // ...
};

Here's my problem.  If I change the signal to take no args using the
preferred or portable syntax I get compilation errors:

class Document
{
public:
    typedef boost::signal< void () >  signal_t;
    // ...

    void append(const char* s)
    {
        m_text += s;
        m_sig(true);
    }
    // ...
};

class View
{
public:
    virtual void refresh() const = 0;
    // ...
};

Compilation output (msvc-7.1):

Compiling...
SignalTest.cpp
c:\Boost\include\boost-1_33_1\boost\bind.hpp(63) : error C2825:
'F::result_type': cannot form a qualified name
        c:\Boost\include\boost-1_33_1\boost\bind\bind_template.hpp(15) : see
reference to class template instantiation 'boost::_bi::result_traits<R,F>'
being compiled
        with
        [
            R=boost::_bi::unspecified,
            F=void (__thiscall View::* )(void) const
        ]
        c:\development\SignalTest\SignalTest.cpp(49) : see reference to
class template instantiation 'boost::_bi::bind_t<R,F,L>' being compiled
        with
        [
            R=boost::_bi::unspecified,
            F=void (__thiscall View::* )(void) const,
            L=boost::_bi::list2<boost::_bi::list_av_2<View
*,boost::arg<1>>::B1,boost::_bi::list_av_2<View *,boost::arg<1>>::B2>
        ]
c:\Boost\include\boost-1_33_1\boost\bind.hpp(63) : error C2039:
'result_type' : is not a member of 'operator``global namespace'''
c:\Boost\include\boost-1_33_1\boost\bind.hpp(63) : error C2146: syntax error
: missing ';' before identifier 'type'
c:\Boost\include\boost-1_33_1\boost\bind.hpp(63) : error C2955:
'boost::_bi::type' : use of class template requires template argument list
        c:\Boost\include\boost-1_33_1\boost\bind.hpp(112) : see declaration
of 'boost::_bi::type'
c:\Boost\include\boost-1_33_1\boost\bind.hpp(63) : fatal error C1903: unable
to recover from previous error(s); stopping compilation

Observed with boost_1_33_1 release on cygwin/gcc-3.4.4 and
msvc-7.1platforms.  Any ideas?

Many thanks in advance,
-allen