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[Astar]コントラクト備忘録26（psp22 Cappedについて）

2023/03/04に公開

WebAssembly

こちらの知見がたまったので、備忘録として残します。

1 概要

psp22 Cappedについて

2 内容

本日は、こちらのOpenBrushのexample（psp22 Capped）に沿って見ていこうと思います。

#![cfg_attr(not(feature = "std"), no_std)]
#![feature(min_specialization)]

#[openbrush::contract]
pub mod my_psp22_capped {
    use openbrush::{
        contracts::psp22::extensions::{
            capped::*,
            mintable::*,
        },
        traits::{
            Storage,
            String,
        },
    };

    #[ink(storage)]
    #[derive(Default, Storage)]
    pub struct Contract {
        #[storage_field]
        psp22: psp22::Data,
        #[storage_field]
        cap: capped::Data,
    }

    impl PSP22 for Contract {}

    impl PSP22Capped for Contract {}

    impl PSP22Mintable for Contract {}

    impl psp22::Transfer for Contract {
        fn _before_token_transfer(
            &mut self,
            _from: Option<&AccountId>,
            _to: Option<&AccountId>,
            _amount: &Balance,
        ) -> Result<(), PSP22Error> {
            // `is_none` means that it is minting
            if _from.is_none() && self._is_cap_exceeded(_amount) {
                return Err(PSP22Error::Custom(String::from("Cap exceeded")))
            }
            Ok(())
        }
    }

    impl Contract {
        /// Constructor which mints `initial_supply` of the token to sender
        /// Will set the token's cap to `cap`
        #[ink(constructor)]
        pub fn new(inital_supply: Balance, cap: Balance) -> Self {
            let mut instance = Self::default();

            assert!(instance._init_cap(cap).is_ok());
            assert!(instance.mint(Self::env().caller(), inital_supply).is_ok());

            instance
        }
    }
}