Am 21.07.2014 17:04, schrieb TheFlyingFiddle:
On Monday, 21 July 2014 at 01:42:58 UTC, Daniel Gibson wrote:
Am 21.07.2014 03:34, schrieb Vlad Levenfeld:
To get a foreach to run at compile-time, you have to give it something
whose value is known to the compiler (so, T and typeof(argTuple) would
suffice, and 0..T.length really should as well).
Yup
I use this when i want a compile time foreach(from a constant number).
It's slightly longer but has worked great for me thus far.
template staticIota(size_t s, size_t e, size_t step = 1)
{
import std.typetuple : TypeTuple;
static if(s < e)
alias staticIota = TypeTuple!(s, staticIota!(s + step, e));
else
alias staticIota = TypeTuple!();
}
Yeah, I had a similar workaround:
template TupleIndicesImpl(alias len, I...)
{
static if(len == I.length) // also handles len == 0
alias TupleIndicesImpl = I;
else static if(I.length == 0)
alias TupleIndicesImpl = TupleIndicesImpl!(len, 0);
else // I contains 0 ... I.length - 1, so add I.length
alias TupleIndicesImpl = TupleIndicesImpl!(len, I, I.length);
}
template TupleIndices(alias len)
{
alias TupleIndices = TupleIndicesImpl!(len);
}
foreach(i; TupleIndices!(myTuple.length) { ... }
At least for iterating over a tuple Vlad's way suggestion
("foreach(i, U; TupleType)") is nicer and more concise.
However, having something like staticIota in the stdlib would probably
make sense.
Cheers,
Daniel
