Modules on Aptos

Aptos allows for permissionless publishing of modules within a package as well as upgrading those that have appropriate compatibility policy set.

A module contains several structs and functions, much like Rust.

During package publishing time, a few constraints are maintained:

• Both Structs and public function signatures are published as immutable.
• The init_module function plays a crucial role in module initialization:
  • When a module is published for the first time (i.e., the module does not exist on-chain), the VM will search for and execute the init_module(account: &signer) function.
  • When upgrading an existing module that is already on-chain, the init_module function will NOT be called.
  • The signer of the account that is publishing the module is passed into the init_module function.
  • This function must be private and not return any value.
  • The init_module function can have at most one parameter, and its type must be &signer
  • The init_module function should not have generic parameters
  • The init_module function is commonly used to initialize module-specific data structures or set initial states.