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subtypes

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.

Get all types which extend, implement, or use the given base type

namespace HH\Facts;

function subtypes<T>(
  classname<T> $base_type,
  ?DeriveFilters<string, dynamic> $filters = NULL,
): vec<string, classname<T>>;

Throws InvalidOperationException if Facts is not enabled.

Parameters​

  • classname<T> $base_type
  • ?DeriveFilters<string, dynamic> $filters = NULL

Returns​

  • vec<string, classname<T>>