Struct swipl::functor::LazyFunctor

pub struct LazyFunctor { /* private fields */ }

A struct which provides a way to delay and cache functor creation.

This struct wraps a static string and an arity and uses it to construct a swipl functor on the first invocation of as_functor. Subsequent invocations will reuse the earlier constructed functor.

The purpose of this struct is to back the implementation of the functor! macro, but it’s also usable on its own.

Implementations

impl LazyFunctor

pub const fn new(name: &'static str, arity: u16) -> Self

Create a new LazyFunctor.

This constructor is const, as all it does is set up the struct. No actual calls into SWI-Prolog happen at this stage.

pub fn as_functor(&self) -> Functor

Create a functor, or return an earlier created functor.

On first call, this will call swipl to create a functor. Subsequent calls will reuse the functor that was retrieved before.