Attribute Macro specialize 

#[specialize]

#[specialize] attribute macro for distributed specialization across files.

Mark individual items as default with #[specialize(default)]. Supports multi-generic constraints.

Usage

trait MyTrait {
    type Output;
    fn describe(&self) -> Self::Output;
}

// Most general (default) implementation
#[specialize(default)]
impl<T> MyTrait for T {
    type Output = ();
    fn describe(&self) -> Self::Output { () }
}

// More specific - with constraint
#[specialize(T: Clone)]
impl<T> MyTrait for T {
    type Output = T;
    fn describe(&self) -> Self::Output { self.clone() }
}

// Multiple generics
#[specialize(T: Clone, U: Copy)]
impl<T, U> Pair<T, U> for (T, U) { ... }

// Most specific - concrete type
#[specialize]
impl MyTrait for String {
    fn describe(&self) -> Self::Output { self.clone() }
}