Question

Module-definition (.def) files provide
the linker with information about
exports, attributes, and other
information about the program to be
linked. A .def file is most useful
when building a DLL. Because there are
linker options that can be used
instead of module-definition
statements, .def files are generally
not necessary. You can also use
__declspec(dllexport) as a way to specify exported functions.

http://msdn.microsoft.com/en-us/library/28d6s79h%28VS.80%29.aspx

I was wondering, should we prefer .def way? or dllexport way?

Answer 1

Module-definition (.def) files provide us with more flexibility to define how data going to be exported.

For example, function exported can be anonymous (identified by ordinal) which prevent people without the declaration information from using it.

It can also ddo function forwarding/redirection as stated below :
http://msdn.microsoft.com/en-us/library/hyx1zcd3(v=VS.80).aspx