DIP 1025--Dynamic Arrays Only Shrink, Never Grow--Community Review Round 1

[Ola Fosheim Grøstad]

On Monday, 11 November 2019 at 17:28:09 UTC, Jonathan M Davis 
wrote:
> How on earth do D dynamic arrays change their type? int[] is 
> always int[].

Well, what we mean by "type" can of course be debated, but anyway:

Case 1:
     char[] a = new char[2];
     writeln(a.ptr);
     if (false) a.length = 1;
     a.length = 2;
     writeln(a.ptr);  // same pointer

Case 2:
     char[] a = new char[2];
     writeln(a.ptr);
     if (true) a.length = 1;
     a.length = 2;
     writeln(a.ptr); // different pointer

So, whether it extends inline depends what you did with the 
object dynamically. It isn't determined statically. Even though 
in this case that would be possible.

Kinda like the difference between an open and closed file, 
whether it is open or not depends on some dynamic external cause 
(if it exists on the files system).