| # Array Macro [](https://travis-ci.org/JoshMcguigan/arr_macro) [](https://crates.io/crates/arr_macro) |
| |
| Array macro helps initialize arrays. It is useful when initializing large arrays (greater than 32 elements), or arrays of types which do not implement the copy or default traits. |
| |
| Array macro is implemented in 100% safe Rust. |
| |
| For further background on the motivation behind this crate, check out [this blog post](https://www.joshmcguigan.com/blog/array-initialization-rust/). |
| |
| ## Usage |
| |
| ```rust |
| #![feature(proc_macro_hygiene)] |
| |
| use arr_macro::arr; |
| |
| fn main() { |
| let x: [Option<String>; 3] = arr![None; 3]; |
| assert_eq!( |
| [None, None, None], |
| x |
| ); |
| |
| // works with all enum types (and impl copy is not required) |
| #[allow(dead_code)] |
| enum MyEnum { |
| A, |
| B |
| } |
| let _: [MyEnum; 33] = arr![MyEnum::A; 33]; |
| |
| // Vec::new() |
| let _: [Vec<String>; 33] = arr![Vec::new(); 33]; |
| |
| // or your own struct type |
| // and you can even use a counter to behave differently based on the array index |
| #[derive(Debug)] |
| struct MyStruct { |
| member: u16, |
| } |
| impl MyStruct { |
| fn new(member: u16) -> Self { |
| MyStruct { member } |
| } |
| } |
| let mut i = 0u16; |
| let x: [MyStruct; 33] = arr![MyStruct::new({i += 1; i - 1}); 33]; |
| |
| assert_eq!(0, x[0].member); |
| assert_eq!(1, x[1].member); |
| assert_eq!(2, x[2].member); |
| } |
| ``` |
| |
| ## License |
| |
| Licensed under either of |
| |
| * Apache License, Version 2.0, ([LICENSE-APACHE](LICENSE-APACHE) or http://www.apache.org/licenses/LICENSE-2.0) |
| * MIT license ([LICENSE-MIT](LICENSE-MIT) or http://opensource.org/licenses/MIT) |
| |
| at your option. |
| |
| ### Contribution |
| |
| Unless you explicitly state otherwise, any contribution intentionally submitted for inclusion in the work by you, as defined in the Apache-2.0 license, shall be dual licensed as above, without any additional terms or conditions. |
