Struct ContextInitHandle 

pub struct ContextInitHandle(/* private fields */);

Identifies the unique context a contextual_var is in.

Each node that sets context-vars have an unique ID, it is different after each (re)init. The contextual var records this ID, and rebuilds when it has changed. The contextualized inner vars are retained locally to the clone of the contextual var.

Implementations

impl ContextInitHandle

pub fn new() -> Self

Generates a new unique handle.

pub const fn no_context() -> Self

Identifies the state before first contextualization.

This is the default value.

pub fn current() -> Self

Gets the current context handle.

Panics

Panics is not called in an app context at least, never returns no_context.

pub fn is_no_context(&self) -> bool

Handle represents the state before first contextualization.

pub fn with_context<R>(&self, action: impl FnOnce() -> R) -> R

Runs action with self as the current context ID.

Note that ContextVar::with_context already calls this method.

Panics

Panics if the handle is_no_context.

pub fn downgrade(&self) -> WeakContextInitHandle

Create a weak handle that can be used to monitor this handle without holding it.

Trait Implementations

impl Clone for ContextInitHandle

fn clone(&self) -> ContextInitHandle

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for ContextInitHandle

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

Formats the value using the given formatter.

impl Default for ContextInitHandle

fn default() -> ContextInitHandle

Returns the “default value” for a type.

impl PartialEq for ContextInitHandle

fn eq(&self, other: &Self) -> bool

Tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &Rhs) -> bool

Tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.

impl Eq for ContextInitHandle