On 03/02/2011 02:24 PM, Steven Schveighoffer wrote:
On Tue, 01 Mar 2011 18:11:00 -0500, bearophile <bearophileh...@lycos.com> wrote:
http://d.puremagic.com/issues/show_bug.cgi?id=5678
I think there is a general bug where any time the compiler uses an enum, it
simply replaces the expression declared for the enum.
So basically
enum TRUE = new DElement(true);
void main()
{
auto delem1 = TRUE;
auto delem2 = TRUE;
assert(delem1 is delem2); // fails
}
gets morphed into this:
void main()
{
auto delem1 = new Delement(true);
auto delem2 = new Delement(true);
assert(delem1 is delem2); // fails
}
Obviously this works great when the enum is a value type or a string literal
(which is created at compile time). However, it is not so great for things like
AAs, array literals, objects, or structs.
I think there are a few of these bugs in bugzilla, and there should be at least
a tracker, and if not, they should all be combined. This is a serious problem
in D, and really creates havoc (both performance-wise and semantically). I
don't anticipate there is an easy fix.
Essentially, I'd say enum is completely useless except for builtin types and
strings.
Thank you Steven & Bearophile. This solves my problem.
I first did not get Bearophile's answer about run/compile-time constants (I
mean enums). I thought the time when they are created is irrelevant, isn't it?
Anyway, placing the constant defs inside a module's <static this () {...}>
block does what I mean. It does, in fact, ensure *unicity*. But I don't really
understand the relation with Steven's explanation above: why/how does the fact
that a constant's def is inside static this() prevent the compiler to rewrite
it like shown above? Also, I basically don't understand why dmd does that
anyway: it's obviously un-ecological ;-)
Denis
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