Hi Asgar, I was compiling pimpl test on Cygwin with g++ 3.4.4 and was failing due to some compiler errors. I fixed and thought you should also know it before getting into review. Please let me know if you need any help. Attached is the diff file. $ g++ -v Reading specs from /usr/lib/gcc/i686-pc-cygwin/3.4.4/specs Configured with: /gcc/gcc-3.4.4/gcc-3.4.4-1/configure --verbose --prefix=/usr --exec-prefix=/usr --sysconfdir=/etc --libdir=/usr/lib --libexecdir=/usr/lib --mandir=/usr/share/man --infodir=/usr/share/info --enable-languages=c,ada,c++,d,f77,java,objc --enable-nls --without-included-gettext --enable-version-specific-runtime-libs --without-x --enable-libgcj --disable-java-awt --with-system-zlib --enable-interpreter --disable-libgcj-debug --enable-threads=posix --enable-java-gc=boehm --disable-win32-registry --enable-sjlj-exceptions --enable-hash-synchronization --enable-libstdcxx-debug : (reconfigured) Thread model: posix gcc version 3.4.4 (cygming special) (gdc 0.12, using dmd 0.125) 1. First of all the pimpl_ptr.hpp is in the wrong directory. Possible location I think would be best is BOOST_ROOT/boost/pimpl_ptr.hpp 2. Some character at 27:7 in test/pimpl_ptr_test.h causes a compiler problem. 3. With 3.4.4 GCC dependent name lookup cause the problem because of which the base class variable you have defined m_pImpl is not reachable from derived class for policies. I modified it to this->m_pImpl everywhere in the derived classes and was able to compile. You can also qualify it completely. 4. And in the pimpl_ptr the same problem exists with get() function which should be calling the policy function. They are also subjected to two stage lookup causing compiler error. I has had to fix it by adding this-> in the beginning. 5. For the above points you need to possibly make necessary changes to accomodate compilers that do not have / or implement two-stage name lookup correctly. Thank you, -- Nitin Motgi NITIN . DOT. MOTGI .AT. GMAIL .DOT. COM