On Tue, 15 Mar 2011 14:54:13 -0400, Jens <[email protected]> wrote:
I didn't ask how to do composition in D. I asked why composition cannot be done via derivation, i.e., the reasoning behind the language design choice. A design faux paus IMO.
Because composition by inheritance can be *completely* implemented using alias this -- a feature that also provides other niceties. Why provide another mechanism to do the exact same thing, just because you are used to it?
Note that "inheritance" is actually done exactly this way in C++, by putting the derived type at the front of the "derived" type, and aliasing all the methods/fields into the derived namespace.
Show me what composition by derivation provides that alias this does not. -Steve
