On Tuesday, 18 August 2015 at 06:27:53 UTC, Ozan wrote:
On Monday, 17 August 2015 at 06:59:51 UTC, BBasile wrote:
On Monday, 17 August 2015 at 05:57:52 UTC, Ozan wrote:
Hi
[...]
Is there any way to get real OOP with D?
Regards, Ozan
Can you name an OOP oriented language that allows this ? Your
example is eroneous OOP.
The 2 other answers you 've got (the first using an interface
and the second using an abstract class) are valid OOP.
One of the fundamental concept OOP is that a function defined
in a class exists also in its subclasses. So how do you
expect `greeting()` to exist in Family if it's only defined in
its sub-classes ?
You can verify that with the 'Liskov substitution principle'
(https://en.wikipedia.org/wiki/Liskov_substitution_principle).
Actually your sample violates this principle.
Languages like Groovy or JavaScript (with the help of
frameworks ;-)
And I believe many more the newer ones. But that's not the
point.
And... This was not a criticism against D (... "bad D, has no
understanding of OOP. Boahh" ;-)
It was only a question about handling of a typical OOP problem
in a class-typed implementation of OOP like D has. Thanks to
every existing or new creative programming language, today we
have so many other ways to solve our programming problems.
Regards Ozan
You example is not valid strongly-typed OOP. In D you could do
something similar but not with the OO paradigm but rather with
compile-time refexion (introspection):
---
import std.stdio;
static bool isFamilyMember(T)()
{
import std.traits: isCallable;
return __traits(hasMember, T, "greeting");
}
void FamilyMemberSayHello(T)(ref T t)
{
static if (isFamilyMember!T)
t.greeting;
}
struct Dad{
void greeting(){"hello from a Dad".writeln;}
}
struct Boy{
void greeting(){"hello from a Boy".writeln;}
}
struct IdiotDuBled{}
void main()
{
auto dad = new Dad;
auto boy = new Boy;
auto idiotDuBled = new IdiotDuBled;
FamilyMemberSayHello(dad);
FamilyMemberSayHello(boy);
FamilyMemberSayHello(idiotDuBled);
}
---
The idea is rather to check at compile time if a variable will
have the "trait" which characterizes a FamilyMember, without
using inheritence.
