https://forum.dlang.org/post/osiiuzwesgmaegekodif@forum.dlang.org

On Monday, 11 May 2020 at 11:37:07 UTC, Mike Parker wrote:
> This is the discussion thread for the Final Review of DIP 1030, "Named Arguments":
>
> https://github.com/dlang/DIPs/blob/7d114c93edb02d8fc4b05f0716bdb6057905fec2/DIPs/DIP1030.md

I dream it will be like this.

1. Of course, named args delimiter is ':'. Same in struct initialization:

    Border b = { width: 1 };

    struct Border {
        int width;
    };


2. Named args in Class constructor:

    // usage
    auto inp = new Input( border: 1 );

    // class
    class Input
    {
       Border border;

       this() {} // human-coded ctor

       // auto generated from "new Row( border: 1 )"
       //   if not found human-coded ctor with same args
       this( Border border )
       {
           this.border = border;

           this(); // call human-coded ctor
       }
    }

3. Named args in Class constructor merged with ctor args:

    // usage
    auto inp = new Input( "Label text", border: 1 );

    // class
    class Input
    {
       Border border;
       string label_text;

       // human-coded ctor
       this( string label_text )
       {
           this.label_text = label_text;
       }

       // auto generated from "new Row( "Label text", border: 1 )"
       //   if not found human-coded ctor with same args
       this( string label_text, Border border )
       {
           this.border = border;

           this( label_text ); // call human coded ctor
       }
    }

4. Of course, all inline:

    // usage
    auto inp = new Input( border: 1, "Label text" );

    // class
    class Input
    {
       Border border;
       string label_text;

       // human coded ctor
       this( string label_text )
       {
           this.label_text = label_text;
       }

       // auto generated from "new Row( border: 1, "Label text" )"
       this( Border border, string label_text )
       {
           // from named args
           this.border = border;

           // inlined from human coded ctor
           this.label_text = label_text;
       }
    }

5. Class fields is named arguments for ctor.

    // for class:
    class Input
    {
       Border border;
       string label_text;
    }

    // possible calls
    auto a1 = Input( border: 1 );
    auto a2 = Input( label_text: "Score" );
    auto a3 = Input( border: 1, label_text: "Score" );
    auto a4 = Input( label_text: "Score", border: 1 );

6. Function named args:

    // usage
    borderedInput( border: 1 );

    // function
    auto borderedInput( Border border )
    {
        return new Input( border: border );
    }


And then we will write clean code for UI, like in Dart/Flutter:

    auto inp = new Input(
        "Label text",
        border : 1,
        child  : new Image(
            src: "info.png"
        )
    );