bank
This document specifies the bank module of the Cosmos SDK.
The bank module is responsible for handling multi-asset coin transfers between accounts and tracking special-case pseudo-transfers which must work differently with particular kinds of accounts (notably delegating/undelegating for vesting accounts). It exposes several interfaces with varying capabilities for secure interaction with other modules which must alter user balances.
In addition, the bank module tracks and provides query support for the total supply of all assets used in the application.
This module will be used in the BlockX Chain.
The
supply functionality:- passively tracks the total supply of coins within a chain,
- provides a pattern for modules to hold/interact with
Coins, and - introduces the invariant check to verify a chain's total supply.
The total
Supply of the network is equal to the sum of all coins from the account. The total supply is updated every time a Coin is minted (eg: as part of the inflation mechanism) or burned (eg: due to slashing or if a governance proposal is vetoed).The supply functionality introduces a new type of
auth.Account which can be used by modules to allocate tokens and in special cases mint or burn tokens. At a base level these module accounts are capable of sending/receiving tokens to and from auth.Account and other module accounts. This design replaces previous alternative designs where, to hold tokens, modules would burn the incoming tokens from the sender account, and then track those tokens internally. Later, in order to send tokens, the module would need to effectively mint tokens within a destination account. The new design removes duplicate logic between modules to perform this accounting.
The
ModuleAccount interface is defined as follows:type ModuleAccount interface {
auth.Account // same methods as the Account interface
GetName() string // name of the module; used to obtain the address
GetPermissions() []string // permissions of module account
HasPermission(string) bool
}
WARNING! Any module or message handler that allows either direct or indirect sending of funds must explicitly guarantee those funds cannot be sent to module accounts (unless allowed).
The supply
Keeper also introduces new wrapper functions for the auth Keeper and the bank Keeper that are related to ModuleAccount in order to be able to:- Get and set
ModuleAccountby providing theName. - Send coins from and to other
ModuleAccountor standardAccount(BaseAccountorVestingAccount) by passing only theName. MintorBurncoins for aModuleAccount(restricted to its permissions).
Each
ModuleAccount has a different set of permissions that provide different object capabilities to perform certain actions. Permissions need to be registered upon the creation of the supply Keeper so that every time a ModuleAccount calls the allowed functions, the Keeper can lookup the permissions to that specific account and perform or not perform the action.The available permissions are:
Minter: allows for a module to mint a specific amount of coins.Burner: allows for a module to burn a specific amount of coins.Staking: allows for a module to delegate and undelegate a specific amount of coins.
Last modified 1yr ago