README.md

slog-try

Convenience macros for logging with an optional slog Logger.

NOTE - See the bottom of this README for another method of using a Logger that doesn't require Option<Logger>

Current Release

Required dependencies

Add slog-try as a dependency in your Cargo.toml file.

[dependencies]
slog-try = "1"

Project setup

Add use statements for the macros you wish to use:

use slog_try::try_info;

Usage example

Consider HasOptLogger, a data strcuture with an optionally attachable logger:

#[derive(Default)]
struct HasOptLogger {
    logger: Option<Logger>,
}

The macros contained in slog-try encapsulate the required boilerplate to use this logger without verifying whether the optional field actually contains a logger or not:

let mut opt_logger = HasOptLogger { logger: None };

// Try to log even if no logger exist
try_info!(opt_logger.logger, "You won't see me output.  The logger is None."; "opt" => "None");
try_info!(opt_logger.logger, #"imatag", "You won't see me output.  The logger is None."; "opt" => "None");

// Setup a `Logger`
let plain = slog_term::PlainSyncDecorator::new(::std::io::stdout());
let logger = Logger::root(slog_term::FullFormat::new(plain)
    .build()
    .fuse(), o!("surname" => "Lava"));

opt_logger.logger = Some(logger);

// Call again with the new attached logger
try_info!(opt_logger.logger, "You will see me output!"; "opt" => "Some");
try_info!(opt_logger.logger, #"imatag", "You will see me output!"; "opt" => "Some");

Using a Discard Logger

You can use slogs Discard drain in lieu of the Option wrapped logger. Like the try_* macros, in case of a none present logger, the discarding logger is going to drop all incoming messages.

How to initialize a discarding logger

use slog::{Logger, Discard, o};

fn main() {
    let logger = Logger::root(Discard, o!());
    info!(logger, "nothing happens");
}