On 3/15/11 4:06 PM, Steven Schveighoffer wrote:
On Tue, 15 Mar 2011 14:54:13 -0400, Jens <j...@somewhere.org> 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
Oh, come on, why use alias this when you can implement it in assembler?
