Implicit Conversions in Struct Construction

[monarch_dodra]

On Friday, 19 October 2012 at 09:36:14 UTC, Jonathan M Davis 
wrote:
> On Friday, October 19, 2012 10:59:07 bearophile wrote:
>> Jonathan M Davis:
>> > Except that that won't work for int or other built-in types,
>> > because they lack constructors.
>> 
>> Isn't it possible to modify D and add constructors to built-in
>> types?
>> 
>> int(10)
>
> Of course, it would be possible. Whether Walter would agree to 
> though, I have
> no idea. C++ allows it only because it allows you to use the 
> cast operator in
> reverse - i.e. int(10) is identical to (int)10 - though it 
> wouldn't need it in
> the OP's example, because it would do the implicit conversion.
>
> What I'd like to see even more is the ability to do
>
> auto i = new int(10);
>
> which would be particularly useful with immutable, since right 
> now, it's
> impossible to create an immutable pointer to int with a value 
> of anything
> other than 0 without casting.
>
> - Jonathan M Davis

You can use the array.ptr "trick" (or exploit):

void main()
{
   immutable int a = 5;
   immutable(int)* p1 = [a].ptr;
   immutable(int*) p2 = [a].ptr;
}

That said, it is ugly as sin, and "new int(5)" should definitely 
supported.

Same thing with structs actually, which can be "agglomerate 
constructed", or "default copy constructed" : If you can write 
"auto a = T(x);" you should be able to write "auto p = new T(x)";