Struct slog::PushFnValue [−][src]
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.
String
s)
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.
#[macro_use] 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| { s.serialize( format_args!( "{}:{}", record.file(), record.line(), ) ) }) )); }
Trait Implementations
impl<F> Value for PushFnValue<F> where
F: 'static + for<'c, 'd> Fn(&'c Record<'d>, PushFnValueSerializer<'c>) -> Result,
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F: 'static + for<'c, 'd> Fn(&'c Record<'d>, PushFnValueSerializer<'c>) -> Result,
Auto Trait Implementations
impl<F> RefUnwindSafe for PushFnValue<F> where
F: RefUnwindSafe,
F: RefUnwindSafe,
impl<F> Send for PushFnValue<F> where
F: Send,
F: Send,
impl<F> Sync for PushFnValue<F> where
F: Sync,
F: Sync,
impl<F> Unpin for PushFnValue<F> where
F: Unpin,
F: Unpin,
impl<F> UnwindSafe for PushFnValue<F> where
F: UnwindSafe,
F: UnwindSafe,
Blanket Implementations
impl<T> Any for T where
T: 'static + ?Sized,
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T: 'static + ?Sized,
impl<T> Borrow<T> for T where
T: ?Sized,
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T: ?Sized,
impl<T> BorrowMut<T> for T where
T: ?Sized,
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T: ?Sized,
pub fn borrow_mut(&mut self) -> &mut T
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impl<T> From<T> for T
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impl<T, U> Into<U> for T where
U: From<T>,
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U: From<T>,
impl<T> SendSyncUnwindSafe for T where
T: Send + Sync + UnwindSafe + ?Sized,
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T: Send + Sync + UnwindSafe + ?Sized,
impl<T, U> TryFrom<U> for T where
U: Into<T>,
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U: Into<T>,
type Error = Infallible
The type returned in the event of a conversion error.
pub fn try_from(value: U) -> Result<T, <T as TryFrom<U>>::Error>
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impl<T, U> TryInto<U> for T where
U: TryFrom<T>,
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U: TryFrom<T>,