Add name hash as const

[bengineer42]

Description

THIS WILL NEED AN UPDATE TO THE SCARB REPO

https://github.com/dojoengine/scarb/blob/fix-unit-type/scarb/Cargo.toml#L49

Before the hash of the model name was computed everyt time it was called, this has been moved to compile time and is now part of the ModelDefinition

pub trait ModelDefinition<T> {
    const NAME_HASH: felt252;
    fn name() -> ByteArray;
    fn layout() -> Layout;
    fn schema() -> Struct;
    fn size() -> Option<usize>;
}

Related issue

Tests

• Yes
• No, because they aren't needed
• No, because I need help

Added to documentation?

• README.md
• Dojo Book
• No documentation needed

Checklist

• I've formatted my code (scripts/rust_fmt.sh, scripts/cairo_fmt.sh)
• I've linted my code (scripts/clippy.sh, scripts/docs.sh)
• I've commented my code
• I've requested a review after addressing the comments

Summary by CodeRabbit

• New Features

  • Introduced a new constant representing a hash of the event or model name, making it accessible in event and model definitions.

• Refactor

  • Updated selector computations for events and models to use the new name hash constant instead of relying on name strings.

[coderabbitai]

"""

Walkthrough

Ohayo sensei! This update introduces a new NAME_HASH constant to both event and model definitions across core and macro crates. Selector computations now use this precomputed hash instead of string-based names, standardizing hash-based identification for events and models. Macro code was extended to generate and embed these hashes.

Changes

Files / Groups	Change Summary
crates/dojo/core/src/event/event.cairo, crates/dojo/core/src/model/definition.cairo	Added const NAME_HASH: felt252; to EventDefinition and ModelDefinition traits.
crates/dojo/core/src/model/model.cairo, crates/dojo/core/src/model/model_value.cairo	Updated selector methods to use selector_from_hashes with NAME_HASH instead of string-based names.
crates/dojo/macros/src/attributes/event.rs, crates/dojo/macros/src/attributes/model.rs	Extended DojoEvent and DojoModel structs with name_hash field; macro now generates NAME_HASH constants.
examples/benchmark/src/model.cairo	Removed trailing blank line in a test function (non-functional change).

Sequence Diagram(s)

sequenceDiagram
    participant Macro as Macro (DojoEvent/DojoModel)
    participant Definition as Event/Model Definition
    participant Selector as Selector Logic

    Macro->>Definition: Generate NAME_HASH constant (felt252)
    Selector->>Definition: Access NAME_HASH
    Selector->>Selector: Compute selector using selector_from_hashes(namespace_hash, NAME_HASH)

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Possibly related PRs

• feat(dojo-core): add selector_from_names for cairo runtime #2219: Introduces selector_from_names utility used for selector computation from namespace and name hashes, foundational for this PR’s selector changes.
• feat(dojo-lang): add bytearray_hash macro #2946: Adds bytearray_hash macro enabling hash computation for names, which this PR uses to generate NAME_HASH constants.
• fix selector functions for models and contracts #2156: Modifies selector computation to use hash-based constants like NAME_HASH, closely related to this PR’s selector refactoring.

Suggested labels

contributor

Suggested reviewers

• glihm
  """

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[glihm]

proc macros have been merged, don't hesitate to rebase. 🫡

[glihm]

@bengineer42 sorry for the delay on that. Would be great to be reworked with the new macros. 🫡