Crate recallable 

Recallable

A crate for handling partial updates to data structures.

This crate provides the Recallable, Recall, and TryRecall traits, along with derive macros for Recallable and Recall, and an attribute macro recallable_model re-exported from recallable_macro for easy derivation.

The crate itself is #![no_std]. Enabling the serde feature does not require std; it only turns on macro-generated serde support, and it remains usable in no_std environments when your serde stack is configured without std.

Motivation

Many systems receive incremental updates where only a subset of fields change or can be considered part of the state. This crate formalizes this pattern by defining a memento type for a structure and providing a consistent way to apply such mementos safely.

The crate intentionally does not prescribe one canonical memento shape for container-like field types. A type may choose whole-value replacement, selective inner updates, or some other domain-specific behavior, and the derive macros defer to that type’s own Recallable::Memento and Recall::recall implementations.

Traits

Recall

A type that can change state by absorbing one companion memento value.

Recallable

A type that declares a companion memento type.

TryRecall

A fallible variant of Recall.

Attribute Macros

recallable_model

Attribute macro that prepares a struct for the Memento pattern.

Derive Macros

Recall

Derive macro that generates the Recall trait implementation.

Recallable

Derive macro that generates a companion memento struct and the Recallable trait impl.