On 5/23/13 6:16 AM, Peter Alexander wrote:
On Thursday, 23 May 2013 at 09:05:02 UTC, Don wrote:
This means that the const variable x has been initialized TWICE!
That's no different from non-const members.
struct Foo { int x = 1; }
Foo f = Foo(2); // f.x is 2
The initialiser is a default value if you don't provide one in the
constructor. If you don't mark a variable as static then it is not
static and needs to be initialised like any other member variable.
This new behaviour is counter-intuitive and introduces a horrible
inconsistency.
It is exactly what happens in C++ and causes no confusion there.
This is totally different to what happens with module constructors
(you get a compile error if you try to set a const global if it
already has an initializer).
In structs/classes, it is not an initialiser, it is a default value in
case you don't provide a different value.
As far as I can tell, this new feature exists only to create bugs. No
use cases for it have been given. I cannot imagine a case where using
this feature would not be a bug.
The use case is simple: to allow non-static const member variables.
The point is, this is a silent change of behavior. (I agree the new
behavior is sensible.)
Andrei
