Trait ink_env::ContractEnv

pub trait ContractEnv {
    type Env: Environment;
}

Stores the used host environment type of the ink! smart contract.

Note

The used host environment can be altered using the env configuration parameter in the #[ink::contract] parameters. For example if the user wanted to use an environment type definition called MyEnvironment they issue the ink! smart contract as follows:

#[ink::contract(env = MyEnvironment)]

Usage: Default Environment

#[ink::contract]
pub mod contract {
    #[ink(storage)]
    pub struct Contract {}

    impl Contract {
        #[ink(constructor)]
        pub fn constructor() -> Self {
            Self {}
        }

        #[ink(message)]
        pub fn message(&self) {}
    }
}

use contract::Contract;


// The following line only compiles successfully if both
// `ink_env::DefaultEnvironment` and `<Contract as ContractEnv>::Env`
// are of the same type.
const _: IsSameType<<Contract as ContractEnv>::Env> =
    <IsSameType<ink_env::DefaultEnvironment>>::new();

Usage: Custom Environment

#[derive(Clone)]
pub struct CustomEnvironment {}

impl Environment for CustomEnvironment {
    const MAX_EVENT_TOPICS: usize = 4;

    type AccountId = <DefaultEnvironment as Environment>::AccountId;
    type Balance = u64;
    type Hash = <DefaultEnvironment as Environment>::Hash;
    type BlockNumber = u32;
    type Timestamp = u64;
    type ChainExtension = <DefaultEnvironment as Environment>::ChainExtension;
}

#[ink::contract(env = super::CustomEnvironment)]
pub mod contract {
    #[ink(storage)]
    pub struct Contract {}

    impl Contract {
        #[ink(constructor)]
        pub fn constructor() -> Self {
            Self {}
        }

        #[ink(message)]
        pub fn message(&self) {}
    }
}

use contract::Contract;

// The following line only compiles successfully if both
// `CustomEnvironment` and `<Contract as ContractEnv>::Env`
// are of the same type.
const _: IsSameType<<Contract as ContractEnv>::Env> =
    <IsSameType<CustomEnvironment>>::new();

fn main() {}

Required Associated Types

type Env: Environment

The environment type.

Implementors