• =?UTF-8?B?0JLQuNGC0LDQu9C40Lkg0KTQsNC0?= =?UTF-8?B?0LXQtdCy?= (32/32) Jan 22 2021 Context:
• =?UTF-8?B?0JLQuNGC0LDQu9C40Lkg0KTQsNC0?= =?UTF-8?B?0LXQtdCy?= (30/34) Jan 22 2021 Of course, we can use 'factory':
• Paul Backus (3/6) Jan 22 2021 You can't; there's no type deduction for constructors.
• tsbockman (6/10) Jan 22 2021 This is the correct way to do it in D; it's annoying, I know.
• =?UTF-8?B?0JLQuNGC0LDQu9C40Lkg0KTQsNC0?= =?UTF-8?B?0LXQtdCy?= (21/28) Jan 22 2021 I want 'this( T )( T data )' deduction:
• Paul Backus (4/6) Jan 23 2021 Here:
• =?UTF-8?B?0JLQuNGC0LDQu9C40Lkg0KTQsNC0?= =?UTF-8?B?0LXQtdCy?= (2/8) Jan 23 2021 Thank!

=?UTF-8?B?0JLQuNGC0LDQu9C40Lkg0KTQsNC0?= =?UTF-8?B?0LXQtdCy?= writes:

Context:
     data + GUI List

Goal:
     auto list = new List( data );

Concept:
     class is created in the usual way : new List( data )
     store inside the class            : T data;
     type T deducted                   : ( T )( T data )


Tried way:
     template List( T )
     {
         class List
         {
             T data;

             this( T data )
             {
                 this.data = data;
             }


             // data usage...
         }
     }


     void main()
     {
         string[] extensions = [ ".d", ".di" ];

     	auto list = new List( extensions );
     }


     Source: https://run.dlang.io/is/Bw2zHB

Question:
     How to implement on D beauty clean flexible code ?
     like a:
         auto list = new List( data );

     How to return from 'List( data )' class type ?

=?UTF-8?B?0JLQuNGC0LDQu9C40Lkg0KTQsNC0?= =?UTF-8?B?0LXQtdCy?= writes:

On Saturday, 23 January 2021 at 05:39:18 UTC, Виталий Фадеев 
wrote:
 Context:
     data + GUI List

 Goal:
     auto list = new List( data );

Of course, we can use 'factory':

     import std.stdio;


     template List( alias T )
     {
         class List
         {
             T data;

             this( T data )
             {
                 this.data = data;
             }


             // data usage...
         }
     }


     auto  listFactory( T )( T data )
     {
         return new List!( T )( data );
     }

     void main()
     {
         string[] extensions = [ ".d", ".di" ];

         auto list = listFactory( extensions );

         //auto list = new List( extensions );
     }

     source: https://run.dlang.io/is/y167tu


But, how to create class instance with type deduction in usual 
way ?

     auto list = new List( extensions );

Paul Backus <snarwin gmail.com> writes:

On Saturday, 23 January 2021 at 05:54:09 UTC, Виталий Фадеев 
wrote:
 But, how to create class instance with type deduction in usual 
 way ?

     auto list = new List( extensions );

You can't; there's no type deduction for constructors.

tsbockman <thomas.bockman gmail.com> writes:

On Saturday, 23 January 2021 at 05:54:09 UTC, Виталий Фадеев 
wrote:
     auto  listFactory( T )( T data )
     {
         return new List!( T )( data );
     }

This is the correct way to do it in D; it's annoying, I know. 
(Personally, I usually shorten `listFactory` to just `list` to 
make the name as similar as possible to the type name, without 
actually causing a collision.)

=?UTF-8?B?0JLQuNGC0LDQu9C40Lkg0KTQsNC0?= =?UTF-8?B?0LXQtdCy?= writes:

On Saturday, 23 January 2021 at 05:54:09 UTC, Виталий Фадеев 
wrote:
 On Saturday, 23 January 2021 at 05:39:18 UTC, Виталий Фадеев 
 wrote:
 Context:
     data + GUI List

 Goal:
     auto list = new List( data );


I want 'this( T )( T data )' deduction:

     class A( T )
     {
         this( T )( T data )
         {
             // ...
         }
     }

What way to implement this ?

Rules:
    1. if class is template
    2. if ctor is template
    3. if ctor template arg have same name with class template arg 
name (example: T )
    4. deduct T of ctor
    5. set type T for class template ( or put in suggestion queue )

Verify, please.

Where source ?
Where deduction implementation ?

Paul Backus <snarwin gmail.com> writes:

On Saturday, 23 January 2021 at 07:17:38 UTC, Виталий Фадеев 
wrote:
 Where source ?
 Where deduction implementation ?

Here:

https://github.com/dlang/dmd/blob/v2.095.0/src/dmd/dtemplate.d#L1308

=?UTF-8?B?0JLQuNGC0LDQu9C40Lkg0KTQsNC0?= =?UTF-8?B?0LXQtdCy?= writes:

On Saturday, 23 January 2021 at 19:19:29 UTC, Paul Backus wrote:
 On Saturday, 23 January 2021 at 07:17:38 UTC, Виталий Фадеев 
 wrote:
 Where source ?
 Where deduction implementation ?

 Here:

 https://github.com/dlang/dmd/blob/v2.095.0/src/dmd/dtemplate.d#L1308

Thank!