Struct Anchor 

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

Available on crate feature bank only.

Proof that the holder runs in bank 0 (the always-mapped region), and so may run a closure across a bank switch via scope / there.

Those operations lend a closure across a switch; the closure’s code must stay mapped while it runs, which only holds for code in bank 0. An Anchor is that guarantee, as a zero-sized Copy capability. The #[bank::main] and #[bank::zero] macros mint one at the top of every body (their code is in bank 0); a #[bank] function gets none, so it cannot reach scope / there, which would otherwise run a banked closure the switch unmaps.

Being Copy, it threads into nested scopes without borrow friction.

Implementations

impl Anchor

pub const unsafe fn assume() -> Anchor

Assert that the calling code runs in bank 0.

Safety

The caller must physically reside in bank 0 (the always-mapped region): a #[bank::main] / #[bank::zero] body, or a plain fn the linker keeps in bank 0. A #[bank] function is not in bank 0 and must never mint one.

An Anchor must also not be moved into #[bank] code: it witnesses that the current code is in bank 0, which carrying it into a banked function would falsify. (Safe code cannot do this: the macro-minted Anchor is hygienic and there is no other safe constructor.)

Trait Implementations

impl !BankSafe for Anchor

impl Clone for Anchor

fn clone(&self) -> Anchor

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Copy for Anchor