supportsInterface0x150b7a02

SupportsInterface refers to a function defined by the ERC-165 standard that allows a smart contract to declare which interfaces it implements. The function signature is supportsInterface(bytes4 interfaceId) external view returns (bool). By exposing this method, contracts enable others to query their capabilities in a standardized way, facilitating interoperability with wallets, marketplaces, and other on-chain services.

How it works: A contract that implements ERC-165 provides a public view function that returns true for interface IDs it supports and false otherwise. The interface ID is a four-byte identifier calculated as the bitwise XOR of the function selectors of all functions in the interface. A function selector is the first four bytes of the keccak-256 hash of the function signature. The standard interface ERC-165 itself has the ID 0x01ffc9a7, and commonly implemented interfaces include ERC-721 (0x80ac58cd) and ERC-1155 (0xd9b67a26).

Usage in practice: When a contract claims support for an interface, clients can test whether the contract implements that interface before interacting with it. In multi-inheritance contracts, supportsInterface typically combines checks using logical OR and often delegates to super to aggregate capabilities from parent contracts. A typical pattern is to return true if interfaceId matches the contract’s own interface or if a parent contract supports it.

Limitations and considerations: supportsInterface is a declarative capability check and does not guarantee all behaviors of an interface will be fully implemented or compliant in all edge cases. It is a widely adopted convention for runtime discovery, but developers should rely on comprehensive testing and formal specifications when integrating with external contracts.