Polkadot SDK: Multi-chain blockchain development framework

use frame_support::{
    dispatch::DispatchResult,
    pallet_prelude::*,
    traits::Get,
};
use frame_system::pallet_prelude::*;
use sp_std::vec::Vec;

#[frame_support::pallet]
pub mod pallet {
    use super::*;

    #[pallet::pallet]
    #[pallet::generate_store(pub(super) trait Store)]
    pub struct Pallet<T>(_);

    #[pallet::config]
    pub trait Config: frame_system::Config {
        type RuntimeEvent: From<Event<Self>> + IsType<<Self as frame_system::Config>::RuntimeEvent>;
        type MaxLength: Get<u32>;
    }

    #[pallet::storage]
    #[pallet::getter(fn something)]
    pub type Something<T> = StorageValue<_, u32>;

    #[pallet::event]
    #[pallet::generate_deposit(pub(super) fn deposit_event)]
    pub enum Event<T: Config> {
        SomethingStored { something: u32, who: T::AccountId },
    }

    #[pallet::error]
    pub enum Error<T> {
        NoneValue,
        StorageOverflow,
    }

    #[pallet::call]
    impl<T: Config> Pallet<T> {
        #[pallet::call_index(0)]
        #[pallet::weight(10_000)]
        pub fn do_something(origin: OriginFor<T>, something: u32) -> DispatchResult {
            let who = ensure_signed(origin)?;
            <Something<T>>::put(something);
            Self::deposit_event(Event::SomethingStored { something, who });
            Ok(())
        }
    }
}