On Mon, 18 Jan 2010 15:35:17 -0500, dsimcha <[email protected]> wrote:
== Quote from Walter Bright ([email protected])'s article
Leandro Lucarella wrote:
> Do you remember when people asked for default immutability? I do :)
Yes, but it would break every other line of code already written in D.
> I like the idea of making x := y an alias for immutable x = y (or even
> enum x = y). That would make this style much more attractive without
> breaking backward compatibility as immutable-by-default would do.
Actually,
const x = y;
is better than immutable, because if y is a T*, it cannot be implicitly
converted to immutable, while it can be implicitly converted to const.
Refresh my memory, is there any difference whatsoever between const and
immutable
for pure value types (int, float, char, etc.), including in terms of the
compiler
optimizations they allow? As far as I can tell, the difference only
comes into
existence when there's indirection involved.
For pure value types (including structs with only pure value types in
them), no there is no difference. That is why such value types are
implicitly convertable to/from mutable, const and immutable because you
always make a complete copy on assignment.
-Steve
