Macro soroban_sdk::log

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

Log a debug event.

Takes a Env, a literal string, and an optional trailing sequence of arguments that may be any value that are convertible to Val. The string and arguments are appended as-is to the log, as the body of a structured diagnostic event. Such events may be emitted from the host as auxiliary diagnostic XDR, or converted to strings later for debugging.

log! statements are only enabled in non optimized builds that have debug-assertions enabled. To enable debug-assertions add the following lines to Cargo.toml, then build with the profile specified, --profile release-with-logs. See the cargo docs for how to use custom profiles.

[profile.release-with-logs]
inherits = "release"
debug-assertions = true

Examples

Log a string:

use soroban_sdk::{log, Env};

let env = Env::default();

log!(&env, "a log entry");

Log a string with values:

use soroban_sdk::{log, symbol_short, Symbol, Env};

let env = Env::default();

let value = 5;
log!(&env, "a log entry", value, symbol_short!("another"));

Assert on logs in tests:

use soroban_sdk::{log, symbol_short, Symbol, Env};

let env = Env::default();

let value = 5;
log!(&env, "a log entry", value, symbol_short!("another"));

use soroban_sdk::testutils::Logs;
let logentry = env.logs().all().last().unwrap().clone();
assert!(logentry.contains("[\"a log entry\", 5, another]"));