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.

Module Usage

This module provides internal functions for use in your custom facets. Import it to access shared logic and storage.

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.

Was this helpful?

Last updated:March 13, 2026