digitalmars.D - parent class get the subclass object

Brian (29/29) Jan 16 2017 Dlang should support such coding. What should I do?

rikki cattermole (19/48) Jan 16 2017 FYI, this would have been more appropriate in D.learn instead of the

Brian (8/64) Jan 16 2017 No, you don't understand I want to express meaning.

Nemanja Boric (32/102) Jan 16 2017 You're missing a cast, since `this` is a reference to a

Brian (2/35) Jan 16 2017 Yes, it's possible, thank you!

Mike Parker (17/23) Jan 16 2017 Perhaps template this parameters [1]:

Dsby (2/29) Jan 16 2017 That Great!
Brian (2/29) Jan 16 2017 Thanks, I think this is the best way!

Brian <zoujiaqing gmail.com> writes:

Dlang should support such coding. What should I do?

import std.stdio : writeln;

abstract class Base(T)
{
     this()
     {
         _this = this;
     }

     void hello()
     {
         _this.world();
     }

     private
     {
         T _this;
     }
}


class Sub : Base!Sub
{
     void world()
     {
         writeln("Hello world");
     }
}

void main()
{
     Sub sub = new Sub;
     sub.hello();
}

Jan 16 2017

rikki cattermole <rikki cattermole.co.nz> writes:

On 17/01/2017 1:15 AM, Brian wrote:
 Dlang should support such coding. What should I do?

 import std.stdio : writeln;

 abstract class Base(T)
 {
     this()
     {
         _this = this;
     }

     void hello()
     {
         _this.world();
     }

     private
     {
         T _this;
     }
 }


 class Sub : Base!Sub
 {
     void world()
     {
         writeln("Hello world");
     }
 }

 void main()
 {
     Sub sub = new Sub;
     sub.hello();
 }

FYI, this would have been more appropriate in D.learn instead of the 
main forum.

import std.stdio;

abstract class Base {
	void hello() {
		world();
	}

	void world();
}

class Sub : Base {
	override void world() {
		writeln("Hello World");
	}
}

void main() {
	Sub sub = new Sub;
	sub.hello();
}

Jan 16 2017

Brian <zoujiaqing gmail.com> writes:

On Monday, 16 January 2017 at 12:20:47 UTC, rikki cattermole 
wrote:
 On 17/01/2017 1:15 AM, Brian wrote:
 Dlang should support such coding. What should I do?

 import std.stdio : writeln;

 abstract class Base(T)
 {
     this()
     {
         _this = this;
     }

     void hello()
     {
         _this.world();
     }

     private
     {
         T _this;
     }
 }


 class Sub : Base!Sub
 {
     void world()
     {
         writeln("Hello world");
     }
 }

 void main()
 {
     Sub sub = new Sub;
     sub.hello();
 }

 FYI, this would have been more appropriate in D.learn instead 
 of the main forum.

 import std.stdio;

 abstract class Base {
 	void hello() {
 		world();
 	}

 	void world();
 }

 class Sub : Base {
 	override void world() {
 		writeln("Hello World");
 	}
 }

 void main() {
 	Sub sub = new Sub;
 	sub.hello();
 }

No, you don't understand I want to express meaning.

other programing language is allow this.

Your code more like the old C++.

If a high-level programing language or need haevy like C++ impl 
code, It's very regret.

Jan 16 2017

Nemanja Boric <4burgos gmail.com> writes:

On Monday, 16 January 2017 at 16:31:41 UTC, Brian wrote:
 On Monday, 16 January 2017 at 12:20:47 UTC, rikki cattermole 
 wrote:
 On 17/01/2017 1:15 AM, Brian wrote:
 Dlang should support such coding. What should I do?

 import std.stdio : writeln;

 abstract class Base(T)
 {
     this()
     {
         _this = this;
     }

     void hello()
     {
         _this.world();
     }

     private
     {
         T _this;
     }
 }


 class Sub : Base!Sub
 {
     void world()
     {
         writeln("Hello world");
     }
 }

 void main()
 {
     Sub sub = new Sub;
     sub.hello();
 }

 FYI, this would have been more appropriate in D.learn instead 
 of the main forum.

 import std.stdio;

 abstract class Base {
 	void hello() {
 		world();
 	}

 	void world();
 }

 class Sub : Base {
 	override void world() {
 		writeln("Hello World");
 	}
 }

 void main() {
 	Sub sub = new Sub;
 	sub.hello();
 }

 No, you don't understand I want to express meaning.

 other programing language is allow this.

 Your code more like the old C++.

 If a high-level programing language or need haevy like C++ impl 
 code, It's very regret.



You're missing a cast, since `this` is a reference to a 
superclass.

import std.stdio : writeln;

abstract class Base(T)
{
     this()
     {
         _this = cast(T)(this);
         assert(_this);
     }

     void hello()
     {
         _this.world();
     }

     private
     {
         T _this;
     }
}


class Sub : Base!Sub
{
     void world()
     {
         writeln("Hello world");
     }
}

void main()
{
     Sub sub = new Sub;
     sub.hello();
}

Jan 16 2017

Brian <zoujiaqing gmail.com> writes:

On Monday, 16 January 2017 at 16:47:09 UTC, Nemanja Boric wrote:
 On Monday, 16 January 2017 at 16:31:41 UTC, Brian wrote:
 [...]

 You're missing a cast, since `this` is a reference to a 
 superclass.

 import std.stdio : writeln;

 abstract class Base(T)
 {
     this()
     {
         _this = cast(T)(this);
         assert(_this);
     }

     void hello()
     {
         _this.world();
     }

     private
     {
         T _this;
     }
 }


 class Sub : Base!Sub
 {
     void world()
     {
         writeln("Hello world");
     }
 }

 void main()
 {
     Sub sub = new Sub;
     sub.hello();
 }

Yes, it's possible, thank you!

Jan 16 2017

Mike Parker <aldacron gmail.com> writes:

On Monday, 16 January 2017 at 16:31:41 UTC, Brian wrote:

 No, you don't understand I want to express meaning.

 other programing language is allow this.

 Your code more like the old C++.

 If a high-level programing language or need haevy like C++ impl 
 code, It's very regret.



Perhaps template this parameters [1]:

```
class Base {
     void hello(this C)() {
         (cast(C)this).world();
     }
}

class Sub:Base {
     void world() { writeln("Hello world"); }
}

void main() {
     auto sub = new Sub;
     sub.hello();
}
```

[1] http://dlang.org/spec/template.html#TemplateThisParameter

Jan 16 2017

Dsby <dushibaiyu yahoo.com> writes:

On Monday, 16 January 2017 at 19:31:50 UTC, Mike Parker wrote:
 On Monday, 16 January 2017 at 16:31:41 UTC, Brian wrote:

 No, you don't understand I want to express meaning.

 other programing language is allow this.

 Your code more like the old C++.

 If a high-level programing language or need haevy like C++ 
 impl code, It's very regret.



 Perhaps template this parameters [1]:

 ```
 class Base {
     void hello(this C)() {
         (cast(C)this).world();
     }
 }

 class Sub:Base {
     void world() { writeln("Hello world"); }
 }

 void main() {
     auto sub = new Sub;
     sub.hello();
 }
 ```

 [1] http://dlang.org/spec/template.html#TemplateThisParameter

That  Great!

Jan 16 2017

Brian <zoujiaqing gmail.com> writes:

On Monday, 16 January 2017 at 19:31:50 UTC, Mike Parker wrote:
 On Monday, 16 January 2017 at 16:31:41 UTC, Brian wrote:

 No, you don't understand I want to express meaning.

 other programing language is allow this.

 Your code more like the old C++.

 If a high-level programing language or need haevy like C++ 
 impl code, It's very regret.



 Perhaps template this parameters [1]:

 ```
 class Base {
     void hello(this C)() {
         (cast(C)this).world();
     }
 }

 class Sub:Base {
     void world() { writeln("Hello world"); }
 }

 void main() {
     auto sub = new Sub;
     sub.hello();
 }
 ```

 [1] http://dlang.org/spec/template.html#TemplateThisParameter

Thanks, I think this is the best way!

Jan 16 2017

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digitalmars.D - parent class get the subclass object