阐述区块链项目DAPP系统开发技术解决方案

// Helper to mint a Kitty.
pub fn mint(
    owner: &T::AccountId,
    dna: Option<[u8; 16]>,
    gender: Option<Gender>,
) -> Result<T::Hash, Error<T>> {
    let kitty = Kitty::<T> {
        dna: dna.unwrap_or_else(Self::gen_dna),
        price: None,
        gender: gender.unwrap_or_else(Self::gen_gender),
        owner: owner.clone(),
    };

    let kitty_id = T::Hashing::hash_of(&kitty);

    // Performs this operation first as it may fail
    let new_cnt = Self::count_for_kitties().checked_add(1)
        .ok_or(<Error<T>>::CountForKittiesOverflow)?;

    // Check if the kitty does not already exist in our storage map
    ensure!(Self::kitties(&kitty_id) == None, <Error<T>>::KittyExists);

    // Performs this operation first because as it may fail
    <KittiesOwned<T>>::try_mutate(&owner, |kitty_vec| {
        kitty_vec.try_push(kitty_id)
    }).map_err(|_| <Error<T>>::ExceedMaxKittyOwned)?;

    <Kitties<T>>::insert(kitty_id, kitty);
    <CountForKitties<T>>::put(new_cnt);
    Ok(kitty_id)
}

#[pallet::event]
#[pallet::generate_deposit(pub(super) fn deposit_event)]
pub enum Event<T: Config>{
    /// A function succeeded. [time, day]
    Success(T::Time, T::Day),
}

Self::deposit_event(Event::Success(var_time, var_day));