Struct slog::PushFnValue[][src]

pub struct PushFnValue<F>(pub F)
    F: 'static + for<'c, 'd> Fn(&'c Record<'d>, PushFnValueSerializer<'c>) -> Result

Lazy Value that writes to Serializer

It's more ergonomic for closures used as lazy values to return type implementing Serialize, but sometimes that forces an allocation (eg. Strings)

In some cases it might make sense for another closure form to be used - one taking a serializer as an argument, which avoids lifetimes / allocation issues.

Generally this method should be used if it avoids a big allocation of Serialize-implementing type in performance-critical logging statement.

extern crate slog;
use slog::{PushFnValue, Logger, Discard};

fn main() {
    // Create a logger with a key-value printing
    // `file:line` string value for every logging statement.
    // `Discard` `Drain` used for brevity.
    let root = Logger::root(Discard, o!(
        "source_location" => PushFnValue(|record , s| {

Trait Implementations

impl<F> Value for PushFnValue<F> where
    F: 'static + for<'c, 'd> Fn(&'c Record<'d>, PushFnValueSerializer<'c>) -> Result

Serialize self into Serializer Read more

Auto Trait Implementations

impl<F> Send for PushFnValue<F> where
    F: Send

impl<F> Sync for PushFnValue<F> where
    F: Sync