Macro trace 

macro_rules! trace {
    (
        name : $name:expr, target : $target:expr, parent : $parent:expr, {
        $($field:tt)* }, $($arg:tt)*
    ) => { ... };
    (
        name : $name:expr, target : $target:expr, parent : $parent:expr,
        $($k:ident).+ $($field:tt)*
    ) => { ... };
    (
        name : $name:expr, target : $target:expr, parent : $parent:expr, ?
        $($k:ident).+ $($field:tt)*
    ) => { ... };
    (
        name : $name:expr, target : $target:expr, parent : $parent:expr, %
        $($k:ident).+ $($field:tt)*
    ) => { ... };
    (name : $name:expr, target : $target:expr, parent : $parent:expr, $($arg:tt)+) => { ... };
    (name : $name:expr, target : $target:expr, { $($field:tt)* }, $($arg:tt)*) => { ... };
    (name : $name:expr, target : $target:expr, $($k:ident).+ $($field:tt)*) => { ... };
    (name : $name:expr, target : $target:expr, ? $($k:ident).+ $($field:tt)*) => { ... };
    (name : $name:expr, target : $target:expr, % $($k:ident).+ $($field:tt)*) => { ... };
    (name : $name:expr, target : $target:expr, $($arg:tt)+) => { ... };
    (target : $target:expr, parent : $parent:expr, { $($field:tt)* }, $($arg:tt)*) => { ... };
    (target : $target:expr, parent : $parent:expr, $($k:ident).+ $($field:tt)*) => { ... };
    (target : $target:expr, parent : $parent:expr, ? $($k:ident).+ $($field:tt)*) => { ... };
    (target : $target:expr, parent : $parent:expr, % $($k:ident).+ $($field:tt)*) => { ... };
    (target : $target:expr, parent : $parent:expr, $($arg:tt)+) => { ... };
    (name : $name:expr, parent : $parent:expr, { $($field:tt)* }, $($arg:tt)*) => { ... };
    (name : $name:expr, parent : $parent:expr, $($k:ident).+ $($field:tt)*) => { ... };
    (name : $name:expr, parent : $parent:expr, ? $($k:ident).+ $($field:tt)*) => { ... };
    (name : $name:expr, parent : $parent:expr, % $($k:ident).+ $($field:tt)*) => { ... };
    (name : $name:expr, parent : $parent:expr, $($arg:tt)+) => { ... };
    (name : $name:expr, { $($field:tt)* }, $($arg:tt)*) => { ... };
    (name : $name:expr, $($k:ident).+ $($field:tt)*) => { ... };
    (name : $name:expr, ? $($k:ident).+ $($field:tt)*) => { ... };
    (name : $name:expr, % $($k:ident).+ $($field:tt)*) => { ... };
    (name : $name:expr, $($arg:tt)+) => { ... };
    (target : $target:expr, { $($field:tt)* }, $($arg:tt)*) => { ... };
    (target : $target:expr, $($k:ident).+ $($field:tt)*) => { ... };
    (target : $target:expr, ? $($k:ident).+ $($field:tt)*) => { ... };
    (target : $target:expr, % $($k:ident).+ $($field:tt)*) => { ... };
    (target : $target:expr, $($arg:tt)+) => { ... };
    (parent : $parent:expr, { $($field:tt)+ }, $($arg:tt)+) => { ... };
    (parent : $parent:expr, $($k:ident).+ = $($field:tt)*) => { ... };
    (parent : $parent:expr, ? $($k:ident).+ = $($field:tt)*) => { ... };
    (parent : $parent:expr, % $($k:ident).+ = $($field:tt)*) => { ... };
    (parent : $parent:expr, $($k:ident).+, $($field:tt)*) => { ... };
    (parent : $parent:expr, ? $($k:ident).+, $($field:tt)*) => { ... };
    (parent : $parent:expr, % $($k:ident).+, $($field:tt)*) => { ... };
    (parent : $parent:expr, $($arg:tt)+) => { ... };
    ({ $($field:tt)+ }, $($arg:tt)+) => { ... };
    ($($k:ident).+ = $($field:tt)*) => { ... };
    (? $($k:ident).+ = $($field:tt)*) => { ... };
    (% $($k:ident).+ = $($field:tt)*) => { ... };
    ($($k:ident).+, $($field:tt)*) => { ... };
    (? $($k:ident).+, $($field:tt)*) => { ... };
    (% $($k:ident).+, $($field:tt)*) => { ... };
    (? $($k:ident).+) => { ... };
    (% $($k:ident).+) => { ... };
    ($($k:ident).+) => { ... };
    ($($arg:tt)+) => { ... };
}

Constructs an event at the trace level.

This functions similarly to the event! macro. See the top-level documentation for details on the syntax accepted by this macro.

Examples

use tracing::trace;
let pos = Position { x: 3.234, y: -1.223 };
let origin_dist = pos.dist(Position::ORIGIN);

trace!(position = ?pos, ?origin_dist);
trace!(
    target: "app_events",
    position = ?pos,
    "x is {} and y is {}",
    if pos.x >= 0.0 { "positive" } else { "negative" },
    if pos.y >= 0.0 { "positive" } else { "negative" }
);
trace!(name: "completed", position = ?pos);