Question

如何对底物哈希特性进行相等比较？

说我有以下代码，其中owned_vec包含Hash的向量：

use support::{decl_module, decl_storage, decl_event, dispatch::Result,
  StorageValue, StorageMap, ensure, traits::Currency };
use system::ensure_signed;

// this is needed when you want to use Vec and Box
use rstd::prelude::*;
use runtime_primitives::traits::{ As, Hash };
use parity_codec::{ Encode, Decode };

// Our own Cat struct
#[derive(Encode, Decode, Default, Clone, PartialEq, Debug)]
pub struct Kitty<Hash, Balance> {
  id: Hash,
  name: Option<Vec<u8>>,
  base_price: Balance, // when 0, it is not for sale
}

// This module's storage items.
decl_storage! {
  trait Store for Module<T: Trait> as CatAuction {
    Kitties get(kitties): map T::Hash => Kitty<T::Hash, T::Balance>;
    KittyOwner get(owner_of): map T::Hash => Option<T::AccountId>;
    OwnedKitties get(kitties_owned): map T::AccountId => Vec<T::Hash> = Vec::new();
  }
}

decl_module! {
  pub struct Module<T: Trait> for enum Call where origin: T::Origin {
    fn deposit_event<T>() = default;

    pub fn transaction(origin, kitty_id: T::Hash) -> Result {
      let sender = ensure_signed(origin)?;
      let kitty_owner = Self::owner_of(kitty_id).ok_or("Kitty has no owner.")?;
      let mut kitty = Self::kitties(kitty_id);

      <OwnedKitties<T>>::mutate(kitty_owner, |owned_vec| {
        let kitty_index = 0;

        for (i, el) in owned_vec.iter().enumerate() {
          // This is where the compilation error occurs!
          if el != kitty.id { continue }
          kitty_index = i;
        }
        owned_vec.remove(kitty_index);
      });

    }    
  }
}

它给了我编译器错误：

no implementation for `&<T as srml_system::Trait>::Hash == <T as srml_system::Trait>::Hash

help: the trait `core::cmp::PartialEq<<T as srml_system::Trait>::Hash>` is not implemented for `&<T as srml_system::Trait>::Hash`
help: consider adding a `where &<T as srml_system::Trait>::Hash: core::cmp::PartialEq<<T as srml_system::Trait>::Hash>` bound

谢谢！

p.s：知道该教程说，在运行时模块的实现中不鼓励循环通过向量。

srml_system :: Trait :: Hash相等性比较

0 个答案: