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copied!<p>Why using a template?</p> <pre><code>#include <cstdio> struct Foo { int a; int b; } foo = {2, 3}; int const (Foo::*mp) = &Foo::b; int main() { printf("%d\n", foo.*mp); return 0; } </code></pre> <p>The following compiles <code>mp</code> to this on gcc-4.4.1 (I don't have access to MSVC at the moment):</p> <pre><code>.globl mp .align 4 .type mp, @object .size mp, 4 mp: .long 4 </code></pre> <p>It is just an offset to the member, which looks pretty compile-time to me.</p> <p>With template, you need to specify the definition outside of the class:</p> <pre><code>#include <cstdio> struct Foo { int m; int r; } foo = {2, 3}; template<int Foo::*Mem> struct B { static int Foo::* const mp; }; template<int Foo::*Mem> int Foo::* const B<Mem>::mp = Mem; int main() { typedef B<&Foo::m> Bm; typedef B<&Foo::r> Br; printf("%d, %d\n", foo.*(Bm::mp), foo.*(Br::mp)); } </code></pre> <p>Which compiles to:</p> <pre><code>g++ -O2 -S -o- b.cc | c++filt ... .weak B<&(Foo::r)>::mp .section .rodata._ZN1BIXadL_ZN3Foo1rEEEE2mpE,"aG",@progbits,B<&(Foo::r)>::mp,comdat .align 4 .type B<&(Foo::r)>::mp, @object .size B<&(Foo::r)>::mp, 4 B<&(Foo::r)>::mp: .long 4 .weak B<&(Foo::m)>::mp .section .rodata._ZN1BIXadL_ZN3Foo1mEEEE2mpE,"aG",@progbits,B<&(Foo::m)>::mp,comdat .align 4 .type B<&(Foo::m)>::mp, @object .size B<&(Foo::m)>::mp, 4 B<&(Foo::m)>::mp: .zero 4 </code></pre> <p>However this all smacks of standard library features reimplementation (see <code>std::tr1::mem_fn</code>).</p>

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