Struct koto_runtime::CallContext

pub struct CallContext<'a> {
    pub vm: &'a mut KotoVm,
    /* private fields */
}

The context provided when a call to a KNativeFunction is made

See also: crate::MethodContext.

Fields

vm: &'a mut KotoVm

The VM making the call

The VM can be used for operations like KotoVm::call_function, although the CallContext::args and CallContext::instance functions return references, so the values need to be cloned before mutable operations can be called.

If a VM needs to be retained after the call, then see KotoVm::spawn_shared_vm.

Implementations

impl<'a> CallContext<'a>

pub fn new(vm: &'a mut KotoVm, frame_base: u8, arg_count: u8) -> Self

Returns a new context for calling external functions

pub fn instance(&self) -> &KValue

Returns the self instance with which the function was called

pub fn args(&self) -> &[KValue]

Returns the function call’s arguments

pub fn instance_and_args( &self, instance_check: impl Fn(&KValue) -> bool, expected_args_message: &str ) -> Result<(&KValue, &[KValue])>

Returns the instance and args with which the function was called

instance_check should check the provided value and return true if it is acceptable as an instance value for the function. If the function was called without an instance (e.g. it’s being called as a standalone function), then the first argument will be checked and returned as the instance. If no instance is available that passes the check, then an ‘expected arguments’ error will be returned with the expected_args_message.

This is used in the core library to allow operations like list.size() to be used in method contexts like [1, 2, 3].to_tuple(), or as standalone functions like to_tuple [1, 2, 3].