On Wed, 16 Mar 2011 08:01:46 -0400, spir <[email protected]> wrote:
composition vs inheritance
I have carefully read the document "Prefer composition to inheritance",
from C++ coding standards, at
http://www.artima.com/cppsource/codestandards3.html, by Herb Sutter and
Andrei Alexandrescu.
In general, I do agree in that composition makes for a simpler scheme,
and more flexible. But when writing D code, I constantly step on the
same issue that without inheritance and (runtime type) polymorphism, I
simply cannot express /very/ common things.
For instance, say I have 3 kinds of Xs X1 X2 X3. I would like to write:
void moveTogether (X[] xs, Vector vector) {
foreach (x ; xs) {
lookAround(x);
x.move(vector);
if (isX3(x)) {
writeln(x.motto);
x.jump();
}
}
}
void lookAround (X x) {...}
From the article: "Of course, these are not arguments against inheritance
per se. Inheritance affords a great deal of power, including
substitutability and/or the ability to override virtual functions."
i.e., use inheritance because your design requires it.
-Steve
