Macro const_str::format

macro_rules! format {
    ($fmt: literal $($args:tt)*) => { ... };
}

Available on crate feature proc only.

Creates a string slice using interpolation of const expressions.

The input type must be one of

• &str
• char
• bool
• u8, u16, u32, u64, u128, usize
• i8, i16, i32, i64, i128, isize

Examples

use const_str::format as const_format;

const PROMPT: &str = "The answer is";
const ANSWER: usize = 42;

const MESSAGE_1: &str = const_format!("{PROMPT} {ANSWER}");
const MESSAGE_2: &str = const_format!("{} {}", PROMPT, ANSWER);
const MESSAGE_3: &str = const_format!("{0} {1}", PROMPT, ANSWER);
const MESSAGE_4: &str = const_format!("{a} {b}", a = PROMPT, b = ANSWER);
const MESSAGE_5: &str = const_format!("{} {a}", PROMPT, a = ANSWER);

assert_eq!(MESSAGE_1, "The answer is 42");
assert_eq!(MESSAGE_1, MESSAGE_2);
assert_eq!(MESSAGE_1, MESSAGE_3);
assert_eq!(MESSAGE_1, MESSAGE_4);
assert_eq!(MESSAGE_1, MESSAGE_5);