Struct initializers as expressions

Marc Sch├╝tz via Digitalmars-d-learn digitalmars-d-learn at puremagic.com
Fri Dec 4 02:42:46 PST 2015


On Thursday, 3 December 2015 at 15:31:49 UTC, Chris Wright wrote:
> On Thu, 03 Dec 2015 06:38:20 +0000, Mike Parker wrote:
>
>> AFAIK, your only option is to use a struct constructor. This 
>> is the sort of thing they're  used for.
>
> Which brings be back to positional arguments, which means that 
> someone wishing to supply a limit on the number of query 
> results must also give me the number of results per page, even 
> if she doesn't care about the number of results per page.
>
> Is it worth posting a DIP for struct literals of the form 
> `Name{fieldname: value}` ?

I'd support that, too.

I suggest to make the struct name optional:

     struct S { int a, b; }
     struct T { string a, b; }
     void foo(S s);
     void foo(T t);

     foo({b: 1, a: 2});  // foo(S(2, 1));
     foo({a: "bla"});    // foo(T("bla", null));

Then we can add some syntax sugar to leave out the braces, too:

     void bar(int a, T t)
     bar(42, a: "bla", b: "xyz");

This effectively gives us strongly typed named arguments, without 
making the names part of the function signature, which Walter 
objected to the last time something like this was proposed.


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