Re: address of virtual member function passed as template argument

From:

"Alex Blekhman" <xfkt@oohay.moc>

Newsgroups:

microsoft.public.vc.language

Date:

Fri, 16 Mar 2007 23:46:49 +0200

Message-ID:

<uhuxbSBaHHA.1400@TK2MSFTNGP06.phx.gbl>

<pascal.zschumme@gmail.com> wrote:

Hello

My problem is that the following code using some very
specific stuff
fails to compile on MSVC8:
<code>
// main.cpp
//
// the error is:
// main.cpp(8) : fatal error C1001: internal compiler
error.// (File
"msc1.cpp", Line 1392)

#include <iostream>

// just a simple class template which "holds" an address
of a member
// function
// i found out that this class doesn't even need to
contain anything
// else than this to produce the error
template<class Class, void(Class::*MemberFunction)()>
class mfaddr_hold
{
};

class Foo
{
public:
       void f1() {}
       virtual void f2() {}
};

class Boom
{
public:
       void f1() {}
       virtual void f2() {}

       mfaddr_hold<Foo, &Foo::f1> h1; // other class,
normal function
-> works
       mfaddr_hold<Foo, &Foo::f2> h2; // other class,
virtual
function -> works
       mfaddr_hold<Boom, &Boom::f1> h3; // same class,
normal
function -> works
       mfaddr_hold<Boom, &Boom::f2> h4; // same class,
virtual
function -> internal compiler error

};

int main(int argc, char* argv[])
{
       return 0;
}

</code>

The Code works with gcc4.
The problem in MSVC8 is that i can't pass the address of a
virtual
member
function of a class (here Boom) to a member variable in
the same class
as template parameter ;)

Do you guys know any solutions to solve this? any
workarounds?

Possible workaround depends on what `mfaddr_hold' actually
does. Using your code I came up with workaround using
`std::mem_fun_t':

#include <functional>

....

class Boom
{
public:
    Boom() :
      h1(&Foo::f1),
      h2(&Foo::f2),
      h3(&Boom::f1),
      h4(&Boom::f2)
    {}

    void f1() {}
    virtual void f2() {}

    std::mem_fun_t<void, Foo> h1;
    std::mem_fun_t<void, Foo> h2;
    std::mem_fun_t<void, Boom> h3;
    std::mem_fun_t<void, Boom> h4;
};

int main()
{
    Boom b;
    Foo f;

    b.h1(&f);
    b.h2(&f);

    b.h3(&b);
    b.h4(&b);

    return 0;
}

Everything compiles and works perfectly.

Alex