5 releases
0.2.3 | Dec 19, 2022 |
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0.2.2 | Jun 16, 2020 |
0.2.1 | Dec 26, 2019 |
0.1.4 | Mar 10, 2017 |
0.1.2 |
|
#5 in #constructs
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Used in 3 crates
10KB
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1 << iota
The iota!
macro constructs a set of related constants.
[dependencies]
iota = "0.2"
use iota::iota;
iota! {
const A: u8 = 1 << iota;
, B
, C
, D
}
fn main() {
assert_eq!(A, 1);
assert_eq!(B, 2);
assert_eq!(C, 4);
assert_eq!(D, 8);
}
Within an iota!
block, the iota
variable is an untyped integer constant
whose value begins at 0 and increments by 1 for every constant declared in
the block.
use iota::iota;
iota! {
const A: u8 = 1 << iota;
, B
const C: i32 = -1; // iota is not used but still incremented
pub const D: u8 = iota * 2;
, E
, F
}
// `iota` begins again from 0 in this block
iota! {
const G: usize = 1 << (iota + 10);
, H
}
fn main() {
assert_eq!(A, 1 << 0);
assert_eq!(B, 1 << 1);
assert_eq!(C, -1);
assert_eq!(D, 3 * 2);
assert_eq!(E, 4 * 2);
assert_eq!(F, 5 * 2);
assert_eq!(G, 1 << (0 + 10));
assert_eq!(H, 1 << (1 + 10));
}
License
Licensed under either of Apache License, Version 2.0 or MIT license at your option.Unless you explicitly state otherwise, any contribution intentionally submitted for inclusion in this crate by you, as defined in the Apache-2.0 license, shall be dual licensed as above, without any additional terms or conditions.