Struct Callable 

pub struct Callable<'a> { /* private fields */ }

A function passed to a HostFunction, which it can call while it runs (ADR 0011). Given by HostCall::function.

Implementations

impl Callable<'_>

pub fn arity(&self) -> usize

The number of declared parameters, as HostFunction::arity gives for a host function.

pub fn call(&self, args: &[Option<JsonValue>]) -> Result<Option<JsonValue>>

Applies the function to args, as $map applies its function: extra arguments are passed on, missing ones are undefined, and the context value is null. A lambda keeps the variables of its definition.

Arguments and the result cross the boundary as JSON, as for the host function itself: a sequence comes back as an array or a single value, and a function as None.

The call is part of the evaluation: it counts as a level of depth and checks the timeout and the cancellation token, its result is limited like the evaluation’s (Options::max_result_size), and an audit shows its steps under the host function’s call. Its errors come back with their codes; returning one ends the evaluation, as any error from the expression does.

Trait Implementations

impl<'a> Clone for Callable<'a>

fn clone(&self) -> Self

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl<'a> Copy for Callable<'a>

impl Debug for Callable<'_>

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

Formats the value using the given formatter.