On Thu, 23 May 2013 19:03:25 -0400, Artur Skawina <[email protected]>
wrote:
On 05/23/13 23:06, Steven Schveighoffer wrote:
compiles:
struct S
{
const int x;
this(int n)
{
x = n;
}
}
It's the 'const int x = 42;' case we're talking about. *That* one does
not
compile and doesn't need to. It /could/, but I see no reason to allow
this;
My example is essentially:
const int x = 0;
It is default initialized to 0, and then the ctor can initialize it to
something else.
To say that
const int x = 42;
is different is inconsistent. Both are consts stored inside each
instance, written by the compiler before the ctor is called. Then the
ctor is free to initialize them away from the default.
What you want is a feature that defines a struct field as always a certain
value and NOT changeable, even in the ctor. As far as I know, that does
not exist in D, and seems specialized to protocol layouts (normally you do
not want to waste memory with a field that never changes and is always
known at compile-time). As the initializer syntax already is taken, you
will need a new syntax, or improve the optimizer to be able to prove this
is the case.
-Steve
