IsInternal

:::info[Note] This is a point-in-time snapshot of the API documentation from January 2026. Going forward, we will not be maintaining a public copy of these references, and recommend users to refer to the built-in signature helpers available in the Hack LSP instead for complete and up-to-date information. :::

( excerpt from http://php.net/manual/en/reflectionclass.isinternal.php )

public function isInternal(): bool;

Checks if the class is defined internally by an extension, or the core, as opposed to user-defined.

Returns

• bool - Returns TRUE on success or FALSE on failure.