lotus/chain/actors/builtin

Actors

This package contains shims for abstracting over different actor versions.

Design

Shims in this package follow a few common design principles.

Structure Agnostic

Shims interfaces defined in this package should (ideally) not change even if the structure of the underlying data changes. For example:

• All shims store an internal "store" object. That way, state can be moved into a separate object without needing to add a store to the function signature.
• All functions must return an error, even if unused for now.

Minimal

These interfaces should be expanded only as necessary to reduce maintenance burden.

Queries, not field assessors.

When possible, functions should query the state instead of simply acting as field assessors. These queries are more likely to remain stable across specs-actor upgrades than specific state fields.

Note: there is a trade-off here. Avoid implementing complicated query logic inside these shims, as it will need to be replicated in every shim.