The Contracts module provides functionality for the runtime to deploy and execute WebAssembly smart-contracts.
This module extends accounts based on the
frame_support::traits::fungible traits to have
smart-contract functionality. It can be used with other modules that implement accounts based on
frame_support::traits::fungible traits. These “smart-contract accounts” have the ability
to instantiate smart-contracts and make calls to other contract and non-contract accounts.
The smart-contract code is stored once, and later retrievable via its hash. This means that multiple smart-contracts can be instantiated from the same hash, without replicating the code each time.
When a smart-contract is called, its associated code is retrieved via the code hash and gets executed. This call can alter the storage entries of the smart-contract account, instantiate new smart-contracts, or call other smart-contracts.
Finally, when an account is reaped, its associated code and storage of the smart-contract account will also be deleted.
Senders must specify a
Weight limit with every call, as all instructions invoked by the
smart-contract require weight. Unused weight is refunded after the call, regardless of the
If the weight limit is reached, then all calls and state changes (including balance transfers) are only reverted at the current call’s contract level. For example, if contract A calls B and B runs out of gas mid-call, then all of B’s calls are reverted. Assuming correct error handling by contract A, A’s other calls and state changes still persist.
Contract call failures are not always cascading. When failures occur in a sub-call, they do not “bubble up”, and the call will only revert at the specific contract level. For example, if contract A calls contract B, and B fails, A can decide how to handle that failure, either proceeding or reverting A’s changes.
Pallet::instantiate_with_code- Deploys a new contract from the supplied Wasm binary, optionally transferring some balance. This instantiates a new smart contract account with the supplied code and calls its constructor to initialize the contract.
Pallet::instantiate- The same as
instantiate_with_codebut instead of uploading new code an existing
Pallet::call- Makes a call to an account, optionally transferring some balance.
Pallet::upload_code- Uploads new code without instantiating a contract from it.
Pallet::remove_code- Removes the stored code and refunds the deposit to its owner. Only allowed to code owner.
Pallet::set_code- Changes the code of an existing contract. Only allowed to
Pallet::migrate- Runs migration steps of current multi-block migration in priority, before
ink!is language that enables writing Wasm-based smart contracts in plain Rust.
pub use crate::debug::Tracing;
pub use crate::migration::MigrateSequence;
pub use crate::migration::Migration;
pub use crate::migration::NoopMigration;
pub use weights::WeightInfo;
pub use crate::pallet::*;
- Documentation of the API (host functions) available to contracts.
- A mechanism for runtime authors to augment the functionality of contracts.
- Multi-block Migration framework for pallet-contracts.
palletmodule in each FRAME pallet hosts the most important items needed to construct this pallet.
- Autogenerated weights for
- Default address generator.
- List of all runtime configurable types that are used in the communication between
pallet-contractsand any given contract.
- Wrapper around
PhantomDatato prevent it being filtered by
- Represents one entry in the call stack.
- Describes the weight for each imported function that a contract is allowed to call.
- Gas metering of Wasm executed instructions is being done on the engine side. This struct holds a reference value used to gas units scaling between host and engine.
- Describes the upper limits on various metrics.
- Definition of the cost schedule and other parameterizations for the wasm vm.
- Determines whether events should be collected during execution.
- Determines whether debug messages will be collected.
- Defines the required determinism level of a wasm blob when either running or uploading code.
- The type of origins supported by the contracts pallet.
- Provides the contract address generation method.
- The API used to dry-run contract interactions.