On 4/24/21 6:50 PM, Jack wrote:
> I'd like to output `K` and get this identifier at compile time.

This is solved by the "this template parameter":

import std.stdio;

class A {
  void showMyName(this T)() {
    writefln("name = [%s]", __traits(identifier, T));
  }
}

class K : A { }

void main() {
  new K().showMyName();
}

Ali

On Sunday, 25 April 2021 at 02:02:47 UTC, Ali Çehreli wrote:
> On 4/24/21 6:50 PM, Jack wrote:
>> I'd like to output `K` and get this identifier at compile time.
>
> This is solved by the "this template parameter":
>
> import std.stdio;
>
> class A {
>   void showMyName(this T)() {
>     writefln("name = [%s]", __traits(identifier, T));
>   }
> }
>
> class K : A { }
>
> void main() {
>   new K().showMyName();
> }
>
> Ali

good one Ali, thanks. Where is this template parameter documented at?

On Sunday, 25 April 2021 at 02:02:47 UTC, Ali Çehreli wrote:
> On 4/24/21 6:50 PM, Jack wrote:
>> I'd like to output `K` and get this identifier at compile time.
>
> This is solved by the "this template parameter":
>
> import std.stdio;
>
> class A {
>   void showMyName(this T)() {
>     writefln("name = [%s]", __traits(identifier, T));
>   }
> }
>
> class K : A { }
>
> void main() {
>   new K().showMyName();
> }
>
> Ali

doesn't this work when called from member in a derived class?

```d

class A
{
	void doSomething(this T)()
	{
		writefln("name = [%s]", __traits(identifier, T));
	}
}

class K : A
{
	void baa()
	{
		doSomething();
	}
}
```

result in the error:

Error: template `foo.A.doSomething` cannot deduce function from argument types `!()()`,

On Sunday, 25 April 2021 at 02:26:00 UTC, Jack wrote:
>
> doesn't this work when called from member in a derived class?
>
> ```d
>
> class A
> {
> 	void doSomething(this T)()
> 	{
> 		writefln("name = [%s]", __traits(identifier, T));
> 	}
> }
>
> class K : A
> {
> 	void baa()
> 	{
> 		doSomething();
> 	}
> }
> ```
>
> result in the error:
>
> Error: template `foo.A.doSomething` cannot deduce function from argument types `!()()`,

It works if you call it with `this.doSomething()`: https://run.dlang.io/is/eIygNG

On Sunday, 25 April 2021 at 02:45:38 UTC, Paul Backus wrote:
> On Sunday, 25 April 2021 at 02:26:00 UTC, Jack wrote:
>>
>> doesn't this work when called from member in a derived class?
>>
>> ```d
>>
>> class A
>> {
>> 	void doSomething(this T)()
>> 	{
>> 		writefln("name = [%s]", __traits(identifier, T));
>> 	}
>> }
>>
>> class K : A
>> {
>> 	void baa()
>> 	{
>> 		doSomething();
>> 	}
>> }
>> ```
>>
>> result in the error:
>>
>> Error: template `foo.A.doSomething` cannot deduce function from argument types `!()()`,
>
> It works if you call it with `this.doSomething()`: https://run.dlang.io/is/eIygNG

that's better, thanks

On Sunday, 25 April 2021 at 03:45:13 UTC, Jack wrote:
> that's better, thanks

Imporant to remember that any compile time thing will be the static type. If someone does:

Base a = new Derived();
a.something();

it will still show up as Base in the this template. The knowledge that it is actually a Derived thing is not there at compile time.

(well ok it kind of is, like the compiler's optimizer can still piece it together by following the flow, but it is no longer known to any template after that assignment.)

On Sunday, 25 April 2021 at 08:36:51 UTC, Adam D. Ruppe wrote:
> On Sunday, 25 April 2021 at 03:45:13 UTC, Jack wrote:
>> that's better, thanks
>
> Imporant to remember that any compile time thing will be the static type. If someone does:
>
> Base a = new Derived();
> a.something();
>
> it will still show up as Base in the this template.

I find out this later. I give up trying to get this in automatic way at compile time

On Sunday, 25 April 2021 at 12:54:43 UTC, Jack wrote:
> I find out this later. I give up trying to get this in automatic way at compile time

That's because the type might not be known at compile time at all, it might come from like a plugin loaded at run time and only ever accessed through the interface.