Re: Abstract classes vs interfaces, casting from void*

2019-08-14 Thread wjoe via Digitalmars-d-learn
On Saturday, 10 August 2019 at 08:20:46 UTC, John Colvin wrote: On Friday, 9 August 2019 at 13:39:53 UTC, Simen Kjærås wrote: Thanks for the extra detail. Is there a solid reason to ever use an interface over an abstract class? (Other than multiple inheritance). I'm such a noob at

Re: Abstract classes vs interfaces, casting from void*

2019-08-11 Thread Alex via Digitalmars-d-learn
On Sunday, 11 August 2019 at 20:32:14 UTC, John Colvin wrote: As I see this, everything you wrote is correct. :) But you compared abstractness with interface usage, initially. So... I would say, interfaces are more like the abstract method case without any function body. But then, you will

Re: Abstract classes vs interfaces, casting from void*

2019-08-11 Thread Jonathan M Davis via Digitalmars-d-learn
On Sunday, August 11, 2019 2:32:14 PM MDT John Colvin via Digitalmars-d- learn wrote: > On Sunday, 11 August 2019 at 20:15:34 UTC, Alex wrote: > > As I see this, everything you wrote is correct. :) > > > > But you compared abstractness with interface usage, initially. > > So... I would say,

Re: Abstract classes vs interfaces, casting from void*

2019-08-11 Thread Adam D. Ruppe via Digitalmars-d-learn
On Sunday, 11 August 2019 at 20:32:14 UTC, John Colvin wrote: E.g. why can I not inherit from multiple 100% abstract empty classes? Wouldn't that be the same as inheriting from multiple interfaces? There's kinda no such thing as 100% empty abstract classes, since they all have the implicit

Re: Abstract classes vs interfaces, casting from void*

2019-08-11 Thread John Colvin via Digitalmars-d-learn
On Sunday, 11 August 2019 at 20:15:34 UTC, Alex wrote: On Sunday, 11 August 2019 at 16:05:20 UTC, John Colvin wrote: I'm trying to narrow down exactly what patterns work with each and how they overlap. What I was trying to get at with the abstract method thing is that abstract class C {

Re: Abstract classes vs interfaces, casting from void*

2019-08-11 Thread Alex via Digitalmars-d-learn
On Sunday, 11 August 2019 at 16:05:20 UTC, John Colvin wrote: I'm trying to narrow down exactly what patterns work with each and how they overlap. What I was trying to get at with the abstract method thing is that abstract class C { void foo(); } is an abstract class with a

Re: Abstract classes vs interfaces, casting from void*

2019-08-11 Thread John Colvin via Digitalmars-d-learn
On Sunday, 11 August 2019 at 15:16:03 UTC, Alex wrote: On Sunday, 11 August 2019 at 13:09:43 UTC, John Colvin wrote: Ok. What would go wrong (in D) if I just replaced every interface with an abstract class? I think there's some confusion here, because B.foo is not abstract. abstract on a

Re: Abstract classes vs interfaces, casting from void*

2019-08-11 Thread Alex via Digitalmars-d-learn
On Sunday, 11 August 2019 at 13:09:43 UTC, John Colvin wrote: Ok. What would go wrong (in D) if I just replaced every interface with an abstract class? I think there's some confusion here, because B.foo is not abstract. abstract on a class is not inherited by its methods.

Re: Abstract classes vs interfaces, casting from void*

2019-08-11 Thread John Colvin via Digitalmars-d-learn
On Saturday, 10 August 2019 at 17:28:32 UTC, Alex wrote: ´´´ void main(){} interface A { void fun(); } abstract class B{ void fun(); } class C : A{ void fun(){} } class D : B{ /*override*/ void fun(){} } ´´´ case 1: interface A and class C implementing interface A: You don't need to "override"

Re: Abstract classes vs interfaces, casting from void*

2019-08-11 Thread John Colvin via Digitalmars-d-learn
On Saturday, 10 August 2019 at 17:46:37 UTC, Timon Gehr wrote: On 10.08.19 16:29, John Colvin wrote: Ok. What would go wrong (in D) if I just replaced every interface with an abstract class? interface A{} interface B{} class C: A,B{ } Yes, I know, I guess it wasn't clear unless you read

Re: Abstract classes vs interfaces, casting from void*

2019-08-10 Thread Timon Gehr via Digitalmars-d-learn
On 10.08.19 16:29, John Colvin wrote: Ok. What would go wrong (in D) if I just replaced every interface with an abstract class? interface A{} interface B{} class C: A,B{ }

Re: Abstract classes vs interfaces, casting from void*

2019-08-10 Thread Alex via Digitalmars-d-learn
On Saturday, 10 August 2019 at 14:29:03 UTC, John Colvin wrote: On Saturday, 10 August 2019 at 10:11:15 UTC, Alex wrote: On Saturday, 10 August 2019 at 08:20:46 UTC, John Colvin wrote: On Friday, 9 August 2019 at 13:39:53 UTC, Simen Kjærås wrote: Thanks for the extra detail. Is there a

Re: Abstract classes vs interfaces, casting from void*

2019-08-10 Thread John Colvin via Digitalmars-d-learn
On Saturday, 10 August 2019 at 10:11:15 UTC, Alex wrote: On Saturday, 10 August 2019 at 08:20:46 UTC, John Colvin wrote: On Friday, 9 August 2019 at 13:39:53 UTC, Simen Kjærås wrote: Thanks for the extra detail. Is there a solid reason to ever use an interface over an abstract class?

Re: Abstract classes vs interfaces, casting from void*

2019-08-10 Thread John Colvin via Digitalmars-d-learn
On Saturday, 10 August 2019 at 10:02:02 UTC, Antonio Corbi wrote: On Saturday, 10 August 2019 at 08:20:46 UTC, John Colvin wrote: On Friday, 9 August 2019 at 13:39:53 UTC, Simen Kjærås wrote: Thanks for the extra detail. Is there a solid reason to ever use an interface over an abstract

Re: Abstract classes vs interfaces, casting from void*

2019-08-10 Thread Alex via Digitalmars-d-learn
On Saturday, 10 August 2019 at 08:20:46 UTC, John Colvin wrote: On Friday, 9 August 2019 at 13:39:53 UTC, Simen Kjærås wrote: Thanks for the extra detail. Is there a solid reason to ever use an interface over an abstract class? (Other than multiple inheritance). I'm such a noob at

Re: Abstract classes vs interfaces, casting from void*

2019-08-10 Thread Antonio Corbi via Digitalmars-d-learn
On Saturday, 10 August 2019 at 08:20:46 UTC, John Colvin wrote: On Friday, 9 August 2019 at 13:39:53 UTC, Simen Kjærås wrote: Thanks for the extra detail. Is there a solid reason to ever use an interface over an abstract class? (Other than multiple inheritance). I'm such a noob at

Re: Abstract classes vs interfaces, casting from void*

2019-08-10 Thread John Colvin via Digitalmars-d-learn
On Friday, 9 August 2019 at 13:39:53 UTC, Simen Kjærås wrote: Thanks for the extra detail. Is there a solid reason to ever use an interface over an abstract class? (Other than multiple inheritance). I'm such a noob at anything related to OO.

Re: Abstract classes vs interfaces, casting from void*

2019-08-10 Thread John Colvin via Digitalmars-d-learn
On Friday, 9 August 2019 at 13:39:53 UTC, Simen Kjærås wrote: We're getting into somewhat advanced topics now. This is described in the Application Binary Interface page of the documentation[0]. In short: classes and interfaces both use a vtable[1] that holds pointers to each of their methods.

Re: Abstract classes vs interfaces, casting from void*

2019-08-09 Thread Simen Kjærås via Digitalmars-d-learn
On Friday, 9 August 2019 at 12:26:59 UTC, John Colvin wrote: import std.stdio; interface I { void foo(); } class C : I { override void foo() { writeln("hi"); } } abstract class AC { void foo(); } class D : AC { override void foo() { writeln("hi"); } } void main() { auto

Re: Abstract classes vs interfaces, casting from void*

2019-08-09 Thread John Colvin via Digitalmars-d-learn
On Friday, 9 August 2019 at 13:19:14 UTC, kinke wrote: On Friday, 9 August 2019 at 12:26:59 UTC, John Colvin wrote: Why is there no "hi" between 0 and 1? Because you are treating the unadjusted object pointer as interface pointer and then call the only virtual function of that interface, in

Re: Abstract classes vs interfaces, casting from void*

2019-08-09 Thread kinke via Digitalmars-d-learn
On Friday, 9 August 2019 at 12:26:59 UTC, John Colvin wrote: Why is there no "hi" between 0 and 1? Because you are treating the unadjusted object pointer as interface pointer and then call the only virtual function of that interface, in the 2nd vtbl slot (after the TypeInfo ptr). Casting a

Abstract classes vs interfaces, casting from void*

2019-08-09 Thread John Colvin via Digitalmars-d-learn
import std.stdio; interface I { void foo(); } class C : I { override void foo() { writeln("hi"); } } abstract class AC { void foo(); } class D : AC { override void foo() { writeln("hi"); } } void main() { auto c = new C(); writeln(0); (cast(I)cast(void*)c).foo();