Macro slog::log
[−]
[src]
macro_rules! log { ($l:expr, $lvl:expr, $tag:expr, $($k:expr => $v:expr),+; $($args:tt)+ ) => { ... }; ($l:expr, $lvl:expr, $tag:expr, $msg:expr,) => { ... }; ($l:expr, $lvl:expr, $tag:expr, $msg:expr) => { ... }; ($l:expr, $lvl:expr, $tag:expr, $msg:expr; $($k:expr => $v:expr),+,) => { ... }; ($l:expr, $lvl:expr, $tag:expr, $msg:expr; $($k:expr => $v:expr),+) => { ... }; ($l:expr, $lvl:expr, $tag:expr, $($args:tt)+) => { ... }; }
Log message a logging record
Use wrappers error!
, warn!
etc. instead
The max_level_*
and release_max_level*
cargo features can be used to
statically disable logging at various levels. See slog notable
details
Use version with longer name if you want to prevent
clash with legacy log
crate macro names.
Supported invocations
Simple
#[macro_use] extern crate slog; fn main() { let drain = slog::Discard; let root = slog::Logger::root( drain, o!("key1" => "value1", "key2" => "value2") ); info!(root, "test info log"; "log-key" => true); }
Note that "key" => value
part is optional:
#[macro_use] extern crate slog; fn main() { let drain = slog::Discard; let root = slog::Logger::root( drain, o!("key1" => "value1", "key2" => "value2") ); info!(root, "test info log"); }
fmt::Arguments
support:
#[macro_use] extern crate slog; fn main() { let drain = slog::Discard; let root = slog::Logger::root(drain, o!("key1" => "value1", "key2" => "value2") ); info!(root, "log-key" => true; "formatted: {}", 1); }
Note that due to macro parsing limitation, the message was moved after the key-value pairs.
Again, "key" => value
part is optional:
#[macro_use] extern crate slog; fn main() { let drain = slog::Discard; let root = slog::Logger::root( drain, o!("key1" => "value1", "key2" => "value2") ); info!(root, "formatted: {}", 1); }
Note: use formatting support only when it really makes sense. Eg. logging
message like "found {} keys"
is against structured logging. It should be
"found keys", "count" => keys_num
instead, so that data is clearly named,
typed and separated from the message.
Tags
All above versions can be supplemented with a tag - string literal prefixed
with #
.
#[macro_use] extern crate slog; fn main() { let drain = slog::Discard; let root = slog::Logger::root(drain, o!("key1" => "value1", "key2" => "value2") ); let ops = 3; info!( root, #"performance-metric", "thread speed"; "ops_per_sec" => ops ); }
See Record::tag()
for more information about tags.