At Fri, 21 Jan 2011 09:01:10 -0500, Stewart, Robert wrote:
Alexander Lamaison wrote:
Rule 35 of C++ Coding Standard by Sutter and Alexandrescu: "Avoid inheriting from classes that were not designed to be classes"
^ base
"Using a standalone class as a base is a serious design error"
The reasons given include undefined behaviour when deleting a std::string* pointing to an instance of the subclass, slicing if extra data is added and pointlessness as the subclass doesn't get any more access to the superclass's implementation that it would have had if it just kept std::string as a member.
If there are no additional members, then slicing and failure to invoke the derivate's destructor cause no problems
None other than undefined behavior. :-) The fact that most compilers and platforms will let you get away with it notwithstanding, I'd like to avoid that. -- Dave Abrahams BoostPro Computing http://www.boostpro.com