Array of structs construction

[Era Scarecrow]

On Saturday, 20 October 2012 at 01:06:57 UTC, bearophile wrote:
> I'd like to write code like this (the constructors of the 
> structs must take 1 argument):
>
> // some imports here
> void main() {
>     BigInt[] data1 = [5, 6, 9];
>     Ranged!(int,5,10)[] data2 = [5, 6, 9];
>     Nibble[] data3 = [1, 2, 15]; // Nibble.sizeof == 1
>     alias Typedef!int Mint;
>     Mint[] data4 = [5, 6, 9];
> }
>
>
> Do you like this feature?
>
> Currently in D you write this, it's not handy if you have many 
> items:
>
> // some imports here
> void main() {
>     auto data1 = [BigInt(5), BigInt(6), BigInt(9)];
>     alias Ranged!(int,5,10) R; // a short name
>     auto data2 = [R(5), R(6), R(9)];
>     auto data3 = [Nibble(1), Nibble(2), Nibble(15)];
>     alias Typedef!int Mint;
>     Mint[] data4 = [Mint(5), Mint(6), Mint(9)];
> }

  Only way i can see this working simply, is if it's auto, at 
least one of the items have to specify it's full type and the 
rest can be ignored. Also it must have a constructor that takes 
that one type of argument. So..

//50 & 100 aren't BigInt, but can be constructed to be one..
  auto bignums = [BigInt(25), 50, 100];

  As for above arrays where the type is known, I can't see a 
reason why it can't work.

  In a large array of static data I've had to make shortcut names 
for several structs in order to keep it readable and 
programmable. This may help in some cases, or perhaps all of them.

  Course this also means if a structure is being initialized then 
perhaps it can be extended. Like the above, except...

  struct S {
    int x,y;
    BigInt z;
  }

  S s = {1,2,3}; //3 converted if BigInt has a constructor for int

//if that's illegal, then you'd do this to make it work instead,
//which seems... unnecessary.
  struct S {
    int x,y;
    BigInt[1] z;
  }

  S s = {1,2,[3]};


  The downside is if there's memory allocation or heavy work that 
can't be done at compile-time then there may be more complex 
issues trying to optimize something. Makes it sorta mixed.