Struct log::kv::Value

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pub struct Value<'v> { /* private fields */ }

Expand description

A value in a structured key-value pair.

Capturing values

There are a few ways to capture a value:

Using the Value::capture_* methods.
Using the Value::from_* methods.
Using the ToValue trait.
Using the standard From trait.

Using the `Value::capture_*` methods

Value offers a few constructor methods that capture values of different kinds. These methods require a T: 'static to support downcasting.

use log::kv::Value;

let value = Value::capture_debug(&42i32);

assert_eq!(Some(42), value.to_i64());

Using the `Value::from_*` methods

Value offers a few constructor methods that capture values of different kinds. These methods don’t require T: 'static, but can’t support downcasting.

use log::kv::Value;

let value = Value::from_debug(&42i32);

assert_eq!(None, value.to_i64());

Using the `ToValue` trait

The ToValue trait can be used to capture values generically. It’s the bound used by Source.

let value = 42i32.to_value();

assert_eq!(Some(42), value.to_i64());

use log::kv::ToValue;

let value = (&42i32 as &dyn Debug).to_value();

assert_eq!(None, value.to_i64());

Using the standard `From` trait

Standard types that implement ToValue also implement From.

use log::kv::Value;

let value = Value::from(42i32);

assert_eq!(Some(42), value.to_i64());

Implementations

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impl<'v> Value<'v>

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pub fn from_any<T>(value: &'v T) -> Self where
T: ToValue,

Get a value from a type implementing ToValue.

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pub fn capture_debug<T>(value: &'v T) -> Self where
T: Debug + 'static,

Get a value from a type implementing std::fmt::Debug.

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pub fn capture_display<T>(value: &'v T) -> Self where
T: Display + 'static,

Get a value from a type implementing std::fmt::Display.

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pub fn from_debug<T>(value: &'v T) -> Self where
T: Debug,

Get a value from a type implementing std::fmt::Debug.

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pub fn from_display<T>(value: &'v T) -> Self where
T: Display,

Get a value from a type implementing std::fmt::Display.

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pub fn from_dyn_debug(value: &'v dyn Debug) -> Self

Get a value from a dynamic std::fmt::Debug.

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pub fn from_dyn_display(value: &'v dyn Display) -> Self

Get a value from a dynamic std::fmt::Display.

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pub fn is<T: 'static>(&self) -> bool

Check whether this value can be downcast to T.

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pub fn downcast_ref<T: 'static>(&self) -> Option<&T>

Try downcast this value to T.

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pub fn visit(&self, visitor: impl Visit<'v>) -> Result<(), Error>

Inspect this value using a simple visitor.

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impl<'v> Value<'v>

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pub fn to_u64(&self) -> Option<u64>

Try convert this value into a u64.

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pub fn to_i64(&self) -> Option<i64>

Try convert this value into a i64.

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pub fn to_u128(&self) -> Option<u128>

Try convert this value into a u128.

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pub fn to_i128(&self) -> Option<i128>

Try convert this value into a i128.

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pub fn to_f64(&self) -> Option<f64>

Try convert this value into a f64.

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pub fn to_char(&self) -> Option<char>

Try convert this value into a char.

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pub fn to_bool(&self) -> Option<bool>

Try convert this value into a bool.

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impl<'v> Value<'v>

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pub fn to_borrowed_str(&self) -> Option<&str>

Try convert this value into a borrowed string.

Trait Implementations

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impl<'v> Debug for Value<'v>

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fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter. Read more

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impl<'v> Display for Value<'v>

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fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter. Read more

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impl<'v> From<&'v NonZeroI128> for Value<'v>

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fn from(v: &'v NonZeroI128) -> Value<'v>

Performs the conversion.

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impl<'v> From<&'v NonZeroU128> for Value<'v>

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fn from(v: &'v NonZeroU128) -> Value<'v>

Performs the conversion.

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impl<'v> From<&'v i128> for Value<'v>

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fn from(value: &'v i128) -> Self

Performs the conversion.

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impl<'v> From<&'v str> for Value<'v>

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fn from(value: &'v str) -> Self

Performs the conversion.

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impl<'v> From<&'v u128> for Value<'v>

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fn from(value: &'v u128) -> Self

Performs the conversion.

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impl<'v> From<NonZeroI16> for Value<'v>

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fn from(value: NonZeroI16) -> Self

Performs the conversion.

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impl<'v> From<NonZeroI32> for Value<'v>

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fn from(value: NonZeroI32) -> Self

Performs the conversion.

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impl<'v> From<NonZeroI64> for Value<'v>

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fn from(value: NonZeroI64) -> Self

Performs the conversion.

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impl<'v> From<NonZeroI8> for Value<'v>

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fn from(value: NonZeroI8) -> Self

Performs the conversion.

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impl<'v> From<NonZeroIsize> for Value<'v>

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fn from(value: NonZeroIsize) -> Self

Performs the conversion.

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impl<'v> From<NonZeroU16> for Value<'v>

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fn from(value: NonZeroU16) -> Self

Performs the conversion.

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impl<'v> From<NonZeroU32> for Value<'v>

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fn from(value: NonZeroU32) -> Self

Performs the conversion.

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impl<'v> From<NonZeroU64> for Value<'v>

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fn from(value: NonZeroU64) -> Self

Performs the conversion.

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impl<'v> From<NonZeroU8> for Value<'v>

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fn from(value: NonZeroU8) -> Self

Performs the conversion.

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impl<'v> From<NonZeroUsize> for Value<'v>

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fn from(value: NonZeroUsize) -> Self

Performs the conversion.

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impl<'v> From<bool> for Value<'v>

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fn from(value: bool) -> Self

Performs the conversion.

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impl<'v> From<char> for Value<'v>

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fn from(value: char) -> Self

Performs the conversion.

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impl<'v> From<f32> for Value<'v>

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fn from(value: f32) -> Self

Performs the conversion.

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impl<'v> From<f64> for Value<'v>

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fn from(value: f64) -> Self

Performs the conversion.

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impl<'v> From<i16> for Value<'v>

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fn from(value: i16) -> Self

Performs the conversion.

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impl<'v> From<i32> for Value<'v>

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fn from(value: i32) -> Self

Performs the conversion.

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impl<'v> From<i64> for Value<'v>

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fn from(value: i64) -> Self

Performs the conversion.

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impl<'v> From<i8> for Value<'v>

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fn from(value: i8) -> Self

Performs the conversion.

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impl<'v> From<isize> for Value<'v>

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fn from(value: isize) -> Self

Performs the conversion.

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impl<'v> From<u16> for Value<'v>

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fn from(value: u16) -> Self

Performs the conversion.

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impl<'v> From<u32> for Value<'v>

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fn from(value: u32) -> Self

Performs the conversion.

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impl<'v> From<u64> for Value<'v>

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fn from(value: u64) -> Self

Performs the conversion.

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impl<'v> From<u8> for Value<'v>

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fn from(value: u8) -> Self

Performs the conversion.

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impl<'v> From<usize> for Value<'v>

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fn from(value: usize) -> Self

Performs the conversion.

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impl<'v> ToValue for Value<'v>

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fn to_value(&self) -> Value<'_>

Perform the conversion.

Auto Trait Implementations

impl<'v> !RefUnwindSafe for Value<'v>

impl<'v> !Send for Value<'v>

impl<'v> !Sync for Value<'v>

impl<'v> Unpin for Value<'v>

impl<'v> !UnwindSafe for Value<'v>

Blanket Implementations

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impl<T> Any for T where
T: 'static + ?Sized,

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fn type_id(&self) -> TypeId

Gets the TypeId of self. Read more

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impl<T> Borrow<T> for T where
T: ?Sized,

const: unstable · source

fn borrow(&self) -> &T

Immutably borrows from an owned value. Read more

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impl<T> BorrowMut<T> for T where
T: ?Sized,

const: unstable · source

fn borrow_mut(&mut self) -> &mut T

Mutably borrows from an owned value. Read more

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impl<T> From<T> for T

const: unstable · source

fn from(t: T) -> T

Returns the argument unchanged.

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impl<T, U> Into for T where
U: From<T>,

const: unstable · source

fn into(self) -> U

Calls U::from(self).

That is, this conversion is whatever the implementation of From<T> for U chooses to do.

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impl<T> ToString for T where
T: Display + ?Sized,

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default fn to_string(&self) -> String

Converts the given value to a String. Read more

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impl<T, U> TryFrom for T where
U: Into<T>,

type Error = Infallible

The type returned in the event of a conversion error.

const: unstable · source

fn try_from(value: U) -> Result<T, <T as TryFrom>::Error>

Performs the conversion.

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impl<T, U> TryInto for T where
U: TryFrom<T>,

type Error = >::Error

The type returned in the event of a conversion error.

const: unstable · source

fn try_into(self) -> Result<U, >::Error>

Performs the conversion.

Struct log::kv::Value

Implementations

impl<'v> Value<'v>

pub fn from_any<T>(value: &'v T) -> Self where T: ToValue,

pub fn capture_debug<T>(value: &'v T) -> Self where T: Debug + 'static,

pub fn capture_display<T>(value: &'v T) -> Self where T: Display + 'static,

pub fn from_debug<T>(value: &'v T) -> Self where T: Debug,

pub fn from_display<T>(value: &'v T) -> Self where T: Display,

pub fn from_dyn_debug(value: &'v dyn Debug) -> Self

pub fn from_dyn_display(value: &'v dyn Display) -> Self

pub fn is<T: 'static>(&self) -> bool

pub fn downcast_ref<T: 'static>(&self) -> Option<&T>

pub fn visit(&self, visitor: impl Visit<'v>) -> Result<(), Error>

impl<'v> Value<'v>

pub fn to_u64(&self) -> Option<u64>

pub fn to_i64(&self) -> Option<i64>

pub fn to_u128(&self) -> Option<u128>

pub fn to_i128(&self) -> Option<i128>

pub fn to_f64(&self) -> Option<f64>

pub fn to_char(&self) -> Option<char>

pub fn to_bool(&self) -> Option<bool>

impl<'v> Value<'v>

pub fn to_borrowed_str(&self) -> Option<&str>

Trait Implementations

impl<'v> Debug for Value<'v>

fn fmt(&self, f: &mut Formatter<'_>) -> Result

impl<'v> Display for Value<'v>

fn fmt(&self, f: &mut Formatter<'_>) -> Result

impl<'v> From<&'v NonZeroI128> for Value<'v>

fn from(v: &'v NonZeroI128) -> Value<'v>

impl<'v> From<&'v NonZeroU128> for Value<'v>

fn from(v: &'v NonZeroU128) -> Value<'v>

impl<'v> From<&'v i128> for Value<'v>

fn from(value: &'v i128) -> Self

impl<'v> From<&'v str> for Value<'v>

fn from(value: &'v str) -> Self

impl<'v> From<&'v u128> for Value<'v>

fn from(value: &'v u128) -> Self

impl<'v> From<NonZeroI16> for Value<'v>

fn from(value: NonZeroI16) -> Self

impl<'v> From<NonZeroI32> for Value<'v>

fn from(value: NonZeroI32) -> Self

impl<'v> From<NonZeroI64> for Value<'v>

fn from(value: NonZeroI64) -> Self

impl<'v> From<NonZeroI8> for Value<'v>

fn from(value: NonZeroI8) -> Self

impl<'v> From<NonZeroIsize> for Value<'v>

fn from(value: NonZeroIsize) -> Self

impl<'v> From<NonZeroU16> for Value<'v>

fn from(value: NonZeroU16) -> Self

impl<'v> From<NonZeroU32> for Value<'v>

fn from(value: NonZeroU32) -> Self

impl<'v> From<NonZeroU64> for Value<'v>

fn from(value: NonZeroU64) -> Self

impl<'v> From<NonZeroU8> for Value<'v>

fn from(value: NonZeroU8) -> Self

impl<'v> From<NonZeroUsize> for Value<'v>

fn from(value: NonZeroUsize) -> Self

impl<'v> From<bool> for Value<'v>

fn from(value: bool) -> Self

impl<'v> From<char> for Value<'v>

fn from(value: char) -> Self

impl<'v> From<f32> for Value<'v>

fn from(value: f32) -> Self

impl<'v> From<f64> for Value<'v>

fn from(value: f64) -> Self

impl<'v> From<i16> for Value<'v>

fn from(value: i16) -> Self

impl<'v> From<i32> for Value<'v>

fn from(value: i32) -> Self

impl<'v> From<i64> for Value<'v>

fn from(value: i64) -> Self

impl<'v> From<i8> for Value<'v>

fn from(value: i8) -> Self

impl<'v> From<isize> for Value<'v>

fn from(value: isize) -> Self

impl<'v> From<u16> for Value<'v>

fn from(value: u16) -> Self

impl<'v> From<u32> for Value<'v>

fn from(value: u32) -> Self

pub fn from_any<T>(value: &'v T) -> Self where
T: ToValue,

pub fn capture_debug<T>(value: &'v T) -> Self where
T: Debug + 'static,

pub fn capture_display<T>(value: &'v T) -> Self where
T: Display + 'static,

pub fn from_debug<T>(value: &'v T) -> Self where
T: Debug,

pub fn from_display<T>(value: &'v T) -> Self where
T: Display,

impl<T> Any for T where
T: 'static + ?Sized,

impl<T> Borrow<T> for T where
T: ?Sized,

impl<T> BorrowMut<T> for T where
T: ?Sized,

impl<T, U> Into<U> for T where
U: From<T>,

impl<T> ToString for T where
T: Display + ?Sized,

impl<T, U> TryFrom<U> for T where
U: Into<T>,

impl<T, U> TryInto<U> for T where
U: TryFrom<T>,