Includes a file and safely transmutes it to a value of an arbitrary type.

The file will be included as a byte array, [u8; N], which will be transmuted to another type, T. T is inferred from the calling context, and must implement FromBytes.

The file is located relative to the current file (similarly to how modules are found). The provided path is interpreted in a platform-specific way at compile time. So, for instance, an invocation with a Windows path containing backslashes \ would not compile correctly on Unix.

include_value! is ignorant of byte order. For byte order-aware types, see the byteorder module.

Examples

Assume there are two files in the same directory with the following contents:

File data (no trailing newline):

abcd

File main.rs:

use zerocopy::include_value;
# macro_rules! include_value {
# ($file:expr) => { zerocopy::include_value!(concat!("../testdata/include_value/", $file)) };
# }

fn main() {
    let as_u32: u32 = include_value!("data");
    assert_eq!(as_u32, u32::from_ne_bytes([b'a', b'b', b'c', b'd']));
    let as_i32: i32 = include_value!("data");
    assert_eq!(as_i32, i32::from_ne_bytes([b'a', b'b', b'c', b'd']));
}

Use in const contexts

This macro can be invoked in const contexts.