Comment by wizofaus

It strikes me as something of a language flaw that without pimpl any addition/removal/ modification of private member functions, or even renaming of private member variables triggers full recompilation of every source file that needs to use a particular class. I understand that changes to the size of the object should do so (even if it's just new private member variables), but if it can be determined by the rules of the language that a particular change to a class definition can't possibly affect other compilation units that happen to use that class, then why can't the compiler automatically determine no recompilation is necessary e.g. by calculating and storing a hash of everything about a class that can potentially have an external effect and comparing that value rather than relying on timestamps...