On Thursday, 1 October 2015 at 00:04:18 UTC, Nordlöw wrote:
How do I check that a template parameter is a CT-value or an
enum symbol?
I want this to restrict the following template:
/** Returns: true iff all values $(D V) are the same. */
template allSame(V...) // TODO restrict to values only
{
static if (V.length <= 1)
enum bool allSame = true;
else
enum bool allSame = V[0] == V[1] && allSame!(V[1..$]);
}
unittest
{
static assert(!allSame!(41, 42));
static assert(allSame!(42, 42, 42));
}
std.traits to the rescue!
http://dlang.org/phobos/std_traits.html#isExpressions
Using isExpressions!V as a template constraint looks like the
behavior you're looking for.