• Cecil Ward (16/16) Sep 08 2020 I can’t remember, do Ada or Modula2 have something like
• Andre Pany (5/9) Sep 08 2020 I hope we have it this year or next year, as we have this DIP
• Cecil Ward (9/19) Sep 08 2020 I wonder if there is any way in which we could combine this with
• Dominikus Dittes Scherkl (5/7) Sep 09 2020 You can define your own types, of course:
• Paul Backus (5/13) Sep 09 2020 import std.typecons: Typedef;
• Cecil Ward (2/18) Sep 09 2020 Brilliant. Thank you Paul.

Cecil Ward <cecil cecilward.com> writes:

I can’t remember, do Ada or Modula2 have something like
      myfunc( x => 100, y => 200, color => blue )        [1]
which has named parameters that can be passed in any order.

Does D have anything like this? If not, would anyone support a 
development like the above [1] ?


If D does not have this, I am wondering about how to write such a 
thing but the cure might very very easily be worse than the 
disease. I have little clue here. I have seen a hack for C 
(written by RevK) that involves assignments to fields in a struct 
and the struct is then passed to a function.

Something like
     myfunc( { field2: 20, field1: 10, fieldstr : "a string" } )   
      [2]
and preprocessor trickery was used to get rid of the unsightly { 
} by making a macro call to a wrapper macro that takes variadic 
... arguments.

Andre Pany <andre s-e-a-p.de> writes:

On Tuesday, 8 September 2020 at 07:43:05 UTC, Cecil Ward wrote:
 I can’t remember, do Ada or Modula2 have something like
      myfunc( x => 100, y => 200, color => blue )        [1]
 which has named parameters that can be passed in any order.

 [...]

I hope we have it this year or next year, as we have this DIP
https://www.github.com/dlang/DIPs/tree/master/DIPs%2FDIP1030.md

Kind regards
Andre

Cecil Ward <cecil cecilward.com> writes:

On Tuesday, 8 September 2020 at 09:40:11 UTC, Andre Pany wrote:
 On Tuesday, 8 September 2020 at 07:43:05 UTC, Cecil Ward wrote:
 I can’t remember, do Ada or Modula2 have something like
      myfunc( x => 100, y => 200, color => blue )        [1]
 which has named parameters that can be passed in any order.

 [...]

 I hope we have it this year or next year, as we have this DIP
 https://www.github.com/dlang/DIPs/tree/master/DIPs%2FDIP1030.md

 Kind regards
 Andre

I wonder if there is any way in which we could combine this with 
strong typing of some sort (how?) to detect errors such as
     int xcoord;
     int ycoord;

     myfunc( x : ycoord, y : xcoord, color : blue )        [3]

where the arguments are the wrong way around. Would have to 
change the types of the xcoord and ycoord variables somehow, 
something I have asked about earlier.

Dominikus Dittes Scherkl <dominikus scherkl.de> writes:

On Tuesday, 8 September 2020 at 13:28:22 UTC, Cecil Ward wrote:
     int xcoord;
     int ycoord;

You can define your own types, of course:

struct xcoord { int x; alias x this; }
struct ycoord { int y; alias y this; }

void myfunc(xcoord x; ycoord y, color c) {}

Paul Backus <snarwin gmail.com> writes:

On Tuesday, 8 September 2020 at 13:28:22 UTC, Cecil Ward wrote:
 I wonder if there is any way in which we could combine this 
 with strong typing of some sort (how?) to detect errors such as
     int xcoord;
     int ycoord;

     myfunc( x : ycoord, y : xcoord, color : blue )        [3]

 where the arguments are the wrong way around. Would have to 
 change the types of the xcoord and ycoord variables somehow, 
 something I have asked about earlier.

import std.typecons: Typedef;

alias XCoord = Typedef!(int, int.init, "XCoord");
alias YCoord = Typedef!(int, int.init, "YCoord");

auto myfunc(XCoord x, YCoord y) { ... }

Cecil Ward <cecil cecilward.com> writes:

On Wednesday, 9 September 2020 at 11:48:28 UTC, Paul Backus wrote:
 On Tuesday, 8 September 2020 at 13:28:22 UTC, Cecil Ward wrote:
 I wonder if there is any way in which we could combine this 
 with strong typing of some sort (how?) to detect errors such as
     int xcoord;
     int ycoord;

     myfunc( x : ycoord, y : xcoord, color : blue )        [3]

 where the arguments are the wrong way around. Would have to 
 change the types of the xcoord and ycoord variables somehow, 
 something I have asked about earlier.

 import std.typecons: Typedef;

 alias XCoord = Typedef!(int, int.init, "XCoord");
 alias YCoord = Typedef!(int, int.init, "YCoord");

 auto myfunc(XCoord x, YCoord y) { ... }

Brilliant. Thank you Paul.