Macro log 

macro_rules! log {
    ( $len:literal, $message:literal $(, $args:expr )* $(,)? ) => { ... };
    ( $message:literal $(, $args:expr )* $(,)? ) => { ... };
}

Available on crate feature macro only.

Companion log! macro.

The macro automates the creation of a Logger object to log a message. It support a limited subset of the format! syntax. The macro parses the format string at compile time and generates the calls to a Logger object to generate the corresponding formatted message.

Arguments

• buffer_len: The length of the buffer to use for the logger (default to 200). This is an optional argument.
• format_string: The literal string to log. This string can contain placeholders {} to be replaced by the arguments.
• args: The arguments to replace the placeholders in the format string. The arguments must implement the Log trait.

Examples

Log a static string:

use solana_program_log::log;

log!("a simple log");

Log a formatted value:

use solana_program_log::log;

let lamports = 1_000_000_000u64;
log!("lamports={}", lamports);

Increase the logger buffer size for larger messages:

use solana_program_log::log;

let lamports = 1_000_000_000u64;
log!(500, "lamports={}", lamports);

Apply precision formatting to integer values:

use solana_program_log::log;

let lamports = 1_000_000_000u64;
log!("lamports (SOL)={:.9}", lamports);

Truncate string values from the start or end:

use solana_program_log::log;

let program_name = "solana-program";
log!("{:<.10}", program_name);
log!("{:>.10}", program_name);

Pass any types that implements Log, including slices:

use solana_program_log::log;

let balances = [1u64, 2u64];
log!("lamports={}", &balances);