Function macro_state::proc_read_state

pub fn proc_read_state(key: &str) -> Result<String>

An analogue for read_state! that should only be used within proc macros.

Reads the state value for the specified key. Since macro_state functions as a compile-time key-value store, proc_read_state attempts to read the state value associaed with the specified key.

The macro will expand into a string literal representing the state value in the event that a value exists for the provided key.

If no value can be found for the provided key (or in the event of any sort of IO error), the macro will raise a compile-time IO error.

Example

use macro_state::*;

proc_write_state("cool key", "something").unwrap();
assert_eq!(proc_read_state("cool key").unwrap(), "something");
let result = proc_read_state("undefined key");
assert!(matches!(result, Err(_)));