Macro elog 

macro_rules! elog {
    ($($arg:tt)*) => { ... };
}

A logging macro that prints the value to stderr, with a newline.

This macro is a more gas-efficient alternative to regular eprintln! statements. It evaluates the given expression and writes its display representation to standard error, followed by a newline.

Examples

let error_code = 404;
elog!("{}", error_code);  // Prints: 404\n
elog!("Error {}: Not Found", error_code);  // Prints: Error 404: Not Found\n

Notes

This macro requires that the expression’s type implements the Display trait.