std​::local_data

Structs

Ref

Enum std::local_data::KeyValue[src]

pub enum KeyValue<T> {
    Key,
}

Variants

Key

Methods

impl<T: 'static> KeyValue<T>

fn replace<T: 'static>(&'static self, data: Option<T>) -> Option<T>

Replaces a value in task local storage.

If this key is already present in TLS, then the previous value is replaced with the provided data, and then returned.

Failure

This function will fail if this key is present in TLS and currently on loan with the get method.

Example

fn main() { local_data_key!(foo: int) assert_eq!(foo.replace(Some(10)), None); assert_eq!(foo.replace(Some(4)), Some(10)); assert_eq!(foo.replace(None), Some(4)); }
local_data_key!(foo: int)

assert_eq!(foo.replace(Some(10)), None);
assert_eq!(foo.replace(Some(4)), Some(10));
assert_eq!(foo.replace(None), Some(4));

fn get<T: 'static>(&'static self) -> Option<Ref<T>>

Borrows a value from TLS.

If None is returned, then this key is not present in TLS. If Some is returned, then the returned data is a smart pointer representing a new loan on this TLS key. While on loan, this key cannot be altered via the replace method.

Example

fn main() { local_data_key!(key: int) assert!(key.get().is_none()); key.replace(Some(3)); assert_eq!(*key.get().unwrap(), 3); }
local_data_key!(key: int)

assert!(key.get().is_none());

key.replace(Some(3));
assert_eq!(*key.get().unwrap(), 3);