Macro batch_impl_delegate 

batch_impl_delegate!() { /* proc-macro */ }

Documentation placeholder for the #delegate directive.

#delegate(args){target} generates one delegation call per selected method: each becomes fn m(&self, ...) -> R { (target).m(...) }. The self argument is skipped; the remaining arguments are forwarded (named params as-is, non-identifier patterns renamed to arg{i} when they cannot be used as an expression).

#[batch_impl(
    Vec<u32> #d_len{self.len()},
    Box<Vec<u32>> #delegate(d_len){**self}
)]
trait MyLen { fn d_len(&self) -> usize; }

Documentation marker only — never call this function.