weight-info.rs

// rought file paths writte above each item.

// pallet-balances::weights.rs
trait WieghtInfo {
    fn transfer() -> u32;
}

// pallet-balances
trait Config {
  type WeightInfo: weights::WeightInfo;
}

impl<T: Config> Pallet {
  fn foo() {
    // tada? not much magic 
    let transfer_weight_info = T::WeightInfo::transfer()
  }
}

// runtime::weights::pallet_balances
struct WeightInfo;
impl pallet_balances::WeightInfo for WeightInfo {
  fn transfer() -> u32 { 42u32 }
}

// runtime 
struct Runtime;
impl pallet_balances::Config for Runtime {
  type WeightInfo = runtime::weights::pallet_balances::WeightInfo
}