Array of subclasses
Hello. I have a class:
abstract class Addon
{
public activate(){...}
...
}
its children:
class A: Addon {... }
class B: Addon {... }
How do I create an array of subclasses Addon? For example, one
could to do so:
T[2] addons = [new A(), new B()];
foreach(T addon; addons){
addon.activate();
}
Re: Array of subclasses
On 10/21/2015 11:14 PM, DarkRiDDeR wrote:
Hello. I have a class:
abstract class Addon
{
public activate(){...}
...
}
its children:
class A: Addon {... }
class B: Addon {... }
How do I create an array of subclasses Addon? For example, one could to
do so:
T[2] addons = [new A(), new B()];
foreach(T addon; addons){
addon.activate();
}
This works:
abstract class Addon {
public void activate() {
}
}
class A: Addon {}
class B: Addon {}
void main() {
Addon[2] addons = [new A(), new B()];
}
This works too:
Addon[] addons = [new A(), new B()];
I am happy to report that even the following works with dmd 2.069.0-b2:
auto addons = [new A(), new B()];
I think the last one used to not work. Apparently now their "common
type" is inferred correctly.
Ali
Re: Array of subclasses
This works:
abstract class Addon {
public void activate() {
}
}
class A: Addon {}
class B: Addon {}
void main() {
Addon[2] addons = [new A(), new B()];
}
This works too:
Addon[] addons = [new A(), new B()];
I am happy to report that even the following works with dmd
2.069.0-b2:
auto addons = [new A(), new B()];
I think the last one used to not work. Apparently now their
"common type" is inferred correctly.
Ali
This variant works strangely. Example:
abstract class Addon
{
public string name = "0";
}
class Users: Addon
{
override
{
public string name = "USERS";
}
}
static final class Core
{
static:
public Addon[] activated;
public Users users;
public void activate()
{
users = new Users;
activated = [new Users, new Users];
}
}
Core.activate();
writeln(Core.users.name ~ "\n" ~ Core.activated[1].name);
Out:
USERS
0
Re: Array of subclasses
On Thursday, 22 October 2015 at 11:02:05 UTC, DarkRiDDeR wrote:
This variant works strangely. Example:
abstract class Addon
{
public string name = "0";
}
class Users: Addon
{
override
{
public string name = "USERS";
}
}
static final class Core
{
static:
public Addon[] activated;
public Users users;
public void activate()
{
users = new Users;
activated = [new Users, new Users];
}
}
Core.activate();
writeln(Core.users.name ~ "\n" ~ Core.activated[1].name);
Out:
USERS
0
First of all, the code does not compile with override. It is
impossible to override a data. Override should be removed.
The reason it works this way is that the first access is to base
class data while the second is to the derived data member.
Re: Array of subclasses
On Thursday, 22 October 2015 at 12:24:05 UTC, Maxim Fomin wrote:
On Thursday, 22 October 2015 at 11:02:05 UTC, DarkRiDDeR wrote:
This variant works strangely. Example:
abstract class Addon
{
public string name = "0";
}
class Users: Addon
{
override
{
public string name = "USERS";
}
}
static final class Core
{
static:
public Addon[] activated;
public Users users;
public void activate()
{
users = new Users;
activated = [new Users, new Users];
}
}
Core.activate();
writeln(Core.users.name ~ "\n" ~ Core.activated[1].name);
Out:
USERS
0
First of all, the code does not compile with override. It is
impossible to override a data. Override should be removed.
The reason it works this way is that the first access is to
base class data while the second is to the derived data member.
I don't need the base class data. How to create a array of
subclasses objects with the derived data members?
Re: Array of subclasses
On Thursday, 22 October 2015 at 06:14:34 UTC, DarkRiDDeR wrote: T[2] addons = [new A(), new B()]; Until pretty recently the compiler was a little picky about the types here so you might have to explicitly cast the first element to the base clas type. T[2] addons = [cast(T) new A(), new B()]; casting just the first element tells it you want them all to be interpreted as the base class. I believe that is fixed in the newest version.
Re: Array of subclasses
On Thursday, 22 October 2015 at 13:29:06 UTC, DarkRiDDeR wrote: I don't need the base class data. How to create a array of subclasses objects with the derived data members? The language is implemented in this way. You have already have the answer: writeln(Core.users.name) Out: USERS
Re: Array of subclasses
I found the following solution:
abstract class Addon
{
public string name = "0";
public void updateOfClassFields()
{
}
}
class Users: Addon
{
override
{
public void updateOfClassFields()
{
name = "USERS";
}
}
}
activated = [new Users, new Users];
activated[1].updateOfClassFields();
writeln(Core.activated[0].name ~ "\n" ~ Core.activated[1].name);
out:
0
USERS
