Macro impl_untyped_binding_expression 

macro_rules! impl_untyped_binding_expression {
    ($ty:ty) => { ... };
}

Implements the value entry, disposable and binding expression traits for a type that implements UntypedBindingExpression: what makes the type a binding expression class deriving from UntypedBindingExpressionBase.

The type holds the base (UntypedBindingExpressionBase::new(this, ..), created with Rc::new_cyclic so that the base knows its expression), returns it from UntypedBindingExpression::base, and overrides description, start_core, stop_core and, where needed, the other members of that trait. It can be defined in any crate:

pub struct ConstantExpression { base: UntypedBindingExpressionBase, value: BoxedValue }

impl UntypedBindingExpression for ConstantExpression {
    fn base(&self) -> &UntypedBindingExpressionBase { &self.base }
    fn description(&self) -> String { "Constant".to_string() }
    fn start_core(&self) { self.base.publish_value(Publish::Value(Some(self.value.clone())), None, false) }
    fn stop_core(&self) {}
}

ferroui_base::impl_untyped_binding_expression!(ConstantExpression);