On Wed, 16 Mar 2011 16:49:53 -0400, Simen kjaeraas <simen.kja...@gmail.com> wrote:
On Wed, 16 Mar 2011 16:23:47 +0100, Steven Schveighoffer <schvei...@yahoo.com> wrote:struct Point2 { int x, y; void draw(Canvas c) {...} } struct Point3 : Point2 { int z; void draw(Canvas c) {...} } Point3 p3; Point2 *p2 = &p3; // what does this do? p2.draw(c);Nothing. You should got a type error upon attempting to assign a p3* to a p2*.
We are assuming struct inheritance works here, as in C++. In C++ I can the address of a derived object to a base class pointer without a cast.
This exact code compiles in C++ except for putting semi-colons after the structs (BTW, I have to mention that I freaking LOVE D for eliminating that) and change p2.draw(c) to p2->draw(c).
Even if you say that you shouldn't be allowed to do that, then you are going to have complaints as to why it's different from C++...
The point is, if we allow inheritance on structs, it causes more confusion to people who expect certain things from inheritance than it beautifies syntax.
-Steve
