On 03/28/2013 06:29 AM, "Artur Zawłocki" <[email protected]>" wrote:
Hi,
DMD (I'm using v2.060) seems to evaluate conditions in static if's from
top to bottom (at least in a given scope). For example, consider the
following program:
module test;
const bool x = true;
const bool y = true;
struct S {
static assert(y);
static if(x)
static const bool y = false;
static if(y)
static const bool x = false;
}
'x' in the first static if condition refers to .x and the static if
introduces S.y to which 'y' in the second static if refers. 'y' in the
static assert also refers to S.y and thus the assertion fails:
test.d(8): Error: static assert (y) is false
Now, I guess if the second static if were evaluated first then 'y' in
the static assert condition would refer to .y and the program would
compile. Note that dmd evaluates the static assert *after* both static
if's.
So clearly D program semantics depends on the order static if's and
static assert's are evaluated. Are there any standard rules here (I
cannot find anything in Language Reference) or is this behaviour
implementation dependent?
Artur
It should behave the "same" as a normal if statement.
Except it is evaluated during compile-time and not runtime.
The only different that I know of is that the brackets will not
introduce a new scope.
string Y;
if(true) {
string x = "I'm not in the same scope as Y";
}
static if(true) {
string z = "but I am";
}
that's the only "gotcha" I know of, and I seems quite intuitive once you
realize why that is the case.
But I can't think of any reason why a compiler would want to mix up the
static if's.... Sounds malicious to me. =P
