import std.stdio;

class A
{
	static int id = 0;
	this()
	{
		writeln("typeid=", typeid(this));
		writeln("id=",typeof(this).id); //how to get runtime type of this ??
	}
}

class B : A
{
	static int id = 1;
}

class C : A
{
	static int id = 2;
}

void main()
{
	A a = new B;
	A b = new C;
}

typeof(this) can get compile time type while typeid yield a runtime TypeInfo instance, but how to get runtime type? I want the output to be "id=1" and "id=2" respectively.

On 2013-10-04 10:03, Zhouxuan wrote:
> import std.stdio;
>
> class A
> {
>      static int id = 0;
>      this()
>      {
>          writeln("typeid=", typeid(this));
>          writeln("id=",typeof(this).id); //how to get runtime type of
> this ??
>      }
> }
>
> class B : A
> {
>      static int id = 1;
> }
>
> class C : A
> {
>      static int id = 2;
> }
>
> void main()
> {
>      A a = new B;
>      A b = new C;
> }
>
> typeof(this) can get compile time type while typeid yield a runtime
> TypeInfo instance, but how to get runtime type? I want the output to be
> "id=1" and "id=2" respectively.

You can do this:

class A
{
    static int id = 0;
    this(this T)()
    {
        writeln("typeid=", typeid(T));
        writeln("id=",T.id); //how to get runtime type of this ??
    }
}

class B : A
{
    static int id = 1;
    this () { super(); }
}

class C : A
{
    static int id = 2;
    this () { super(); }
}

void main()
{
    A a = new B;
    A b = new C;
}

Put I'm guess you want to avoid the constructor in the subclasses. I think there's a bug report about this.

-- 
/Jacob Carlborg

On Friday, 4 October 2013 at 08:23:11 UTC, Jacob Carlborg wrote:
> On 2013-10-04 10:03, Zhouxuan wrote:
>> import std.stdio;
>>
>> class A
>> {
>>     static int id = 0;
>>     this()
>>     {
>>         writeln("typeid=", typeid(this));
>>         writeln("id=",typeof(this).id); //how to get runtime type of
>> this ??
>>     }
>> }
>>
>> class B : A
>> {
>>     static int id = 1;
>> }
>>
>> class C : A
>> {
>>     static int id = 2;
>> }
>>
>> void main()
>> {
>>     A a = new B;
>>     A b = new C;
>> }
>>
>> typeof(this) can get compile time type while typeid yield a runtime
>> TypeInfo instance, but how to get runtime type? I want the output to be
>> "id=1" and "id=2" respectively.
>
> You can do this:
>
> class A
> {
>     static int id = 0;
>     this(this T)()
>     {
>         writeln("typeid=", typeid(T));
>         writeln("id=",T.id); //how to get runtime type of this ??
>     }
> }
>
> class B : A
> {
>     static int id = 1;
>     this () { super(); }
> }
>
> class C : A
> {
>     static int id = 2;
>     this () { super(); }
> }
>
> void main()
> {
>     A a = new B;
>     A b = new C;
> }
>
> Put I'm guess you want to avoid the constructor in the subclasses. I think there's a bug report about this.

This is exactly what I want, thank you very much!
Redundant constructor here is not a problem, however there're so many workarounds atm.

On Friday, 4 October 2013 at 08:23:11 UTC, Jacob Carlborg wrote:
> On 2013-10-04 10:03, Zhouxuan wrote:
>> import std.stdio;
>>
>> class A
>> {
>>     static int id = 0;
>>     this()
>>     {
>>         writeln("typeid=", typeid(this));
>>         writeln("id=",typeof(this).id); //how to get runtime type of
>> this ??
>>     }
>> }
>>
>> class B : A
>> {
>>     static int id = 1;
>> }
>>
>> class C : A
>> {
>>     static int id = 2;
>> }
>>
>> void main()
>> {
>>     A a = new B;
>>     A b = new C;
>> }
>>
>> typeof(this) can get compile time type while typeid yield a runtime
>> TypeInfo instance, but how to get runtime type? I want the output to be
>> "id=1" and "id=2" respectively.
>
> You can do this:
>
> class A
> {
>     static int id = 0;
>     this(this T)()
>     {
>         writeln("typeid=", typeid(T));
>         writeln("id=",T.id); //how to get runtime type of this ??
>     }
> }
>
> class B : A
> {
>     static int id = 1;
>     this () { super(); }
> }
>
> class C : A
> {
>     static int id = 2;
>     this () { super(); }
> }
>
> void main()
> {
>     A a = new B;
>     A b = new C;
> }
>
> Put I'm guess you want to avoid the constructor in the subclasses. I think there's a bug report about this.

Unfortunately it doesn't work if C inherits from B.

I am afraid if you want true polymorphic behavior, `id` needs to become a virtual getter function. D runtime reflection is quite lacking in that are.

On 2013-10-04 10:42, Zhouxuan wrote:

> Unfortunately it doesn't work if C inherits from B.

What you need is a template constructor in B, just as in A. But it seems it's not possible to forward the template type to the base class.

-- 
/Jacob Carlborg