substrate-knowledge-map

Quiz 7: Contracts

Overview

This quiz covers the following parts of the Substrate Knowledge Map:

• Smart Contract
• Using ink!

1. What pallets and functionalities does Substrate provide to support Smart Contract execution? Check all that apply.

• pallet-contracts: Offers functionality for a Substrate runtime to deploy and execute WebAssembly smart contracts.
• pallet-evm: Allows unmodified EVM code to be executed in a Substrate-based blockchain.
• pallet-treasury: Provides a “pot” of funds to be deducted when running transactions on smart contracts.
• pallet-membership: Contains the logic for managing the access control of the smart contract on who can call which functions.

2. How does Substrate implement functionality for running Solidity code?

• It sends cross-chain messages over to Ethereum network.
• It embeds a SputnikVM EVM engine to run solidity ABI code.
• It implements the EVM engine specification in pallet-contracts.
• It creates a simulated environment for running EVM code, and puts the final computed result back to the on-chain stroage.

3. What is true about Smart Contracts in Substrate?

• You can deploy a contract once and instantiate it multiple times.
• When you build a contract, three files are generated: a Wasm binary, the native binary, and the metadata files.
• Contracts are intended to be used by any user on a public network. But a contract can specify certain other contracts to modify its own storage directly.
• A contract account is charged proportionally to the amount of storage its account uses. When a contract’s balance goes below a defined limit, the contract’s account is turned into a “tombstone” and its storage is cleaned up.