ERC-165 Module

ERC-165 standard interface detection

Key Features

• Internal functions for registering ERC-165 supported interfaces.
• Utilizes diamond storage pattern via a fixed STORAGE_POSITION.
• No external dependencies, promoting composability.
• Compatible with ERC-2535 diamond proxy standard.

Overview

This module provides internal functions and storage for ERC-165 interface detection within a diamond. Facets import this module to register supported interfaces during initialization using shared diamond storage. This ensures consistent interface identification across all facets of the diamond.

Storage

ERC165Storage

Definition

struct ERC165Storage {
  /*
  * @notice Mapping of interface IDs to whether they are supported
  */
  mapping(bytes4 => bool) supportedInterfaces;
}

State Variables

Property	Type	Description
STORAGE_POSITION	bytes32	Diamond storage slot position for this module (Value: keccak256("erc165"))

Functions

getStorage

Returns a pointer to the ERC-165 storage struct. Uses inline assembly to bind the storage struct to the fixed storage position.

function getStorage() pure returns (ERC165Storage storage s);

Returns:

Property	Type	Description
s	ERC165Storage	The ERC-165 storage struct.

---

registerInterface

Register that a contract supports an interface Call this function during initialization to register supported interfaces. For example, in an ERC721 facet initialization, you would call: LibERC165.registerInterface(type(IERC721).interfaceId)

function registerInterface(bytes4 _interfaceId) ;

Parameters:

Property	Type	Description
_interfaceId	bytes4	The interface ID to register

Best Practices

Best Practice

• Call registerInterface during facet initialization to declare supported interfaces.
• Ensure the diamond's storage layout is compatible with ERC165Mod's storage requirements.
• Verify that the STORAGE_POSITION for ERC-165 is unique and not colliding with other diamond storage.

Integration Notes

Shared Storage

This module interacts with diamond storage at a specific, predefined slot identified by STORAGE_POSITION (keccak256("erc165")). The ERC165Storage struct is managed at this location. The getStorage function returns a pointer to this struct, allowing internal operations. Changes made via registerInterface directly update this shared storage, making them immediately visible to any other facet accessing the same storage position.

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Last updated:March 13, 2026