Trait Callable 

pub trait Callable {
    // Required method
    fn metadata(&self) -> Rc<CallableMetadata>;

    // Provided methods
    fn exec(&self, _scope: Scope<'_>) -> CallResult<()> { ... }
    fn async_exec<'life0, 'life1, 'async_trait>(
        &'life0 self,
        _scope: Scope<'life1>,
    ) -> Pin<Box<dyn Future<Output = CallResult<()>> + 'async_trait>>
       where Self: 'async_trait,
             'life0: 'async_trait,
             'life1: 'async_trait { ... }
}

A trait to define a callable that is executed by a Machine.

The callable themselves are immutable but they can reference mutable state. Given that EndBASIC is not threaded, it is sufficient for those references to be behind a RefCell and/or an Rc.

Idiomatically, these objects need to provide a new() method that returns an Rc<Callable>, as that’s the type used throughout the execution engine.

Required Methods

fn metadata(&self) -> Rc<CallableMetadata>

Returns the metadata for this function.

The return value takes the form of a reference to force the callable to store the metadata as a struct field so that calls to this function are guaranteed to be cheap.

Provided Methods

fn exec(&self, _scope: Scope<'_>) -> CallResult<()>

Executes the callable if it is synchronous.

fn async_exec<'life0, 'life1, 'async_trait>( &'life0 self, _scope: Scope<'life1>, ) -> Pin<Box<dyn Future<Output = CallResult<()>> + 'async_trait>>

where Self: 'async_trait, 'life0: 'async_trait, 'life1: 'async_trait,

Executes the callable if it is asynchronous.

Dyn Compatibility

This trait is dyn compatible.

In older versions of Rust, dyn compatibility was called "object safety".

Implementors