---
title: UFunctions
source: https://dev.epicgames.com/documentation/en-us/unreal-engine/ufunctions-in-unreal-engine
version: Unreal Engine 5.8 Documentation
fetched: 2026-10-11
note: 原文摘录（英文），供 wiki 引用；非全文
---

# UFunctions

- A UFunction is a C++ function that is recognized by the Unreal Engine reflection system. `UFUNCTION([specifier...], [meta(...)])` placed on the line above the declaration in the header.
- UFunctions can bind to Delegates, act as network callbacks, and implement console commands (Exec).
- Specifiers:
  - BlueprintCallable: can be executed in a Blueprint graph.
  - BlueprintImplementableEvent: can be implemented in a Blueprint graph.
  - BlueprintNativeEvent: designed to be overridden by a Blueprint, but also has a default native implementation in `<Name>_Implementation`; autogenerated code calls `_Implementation` if no Blueprint override is found.
  - BlueprintPure: does not affect the owning object; const functions are exposed as pure by default (use BlueprintPure=false to change). Pure functions do not cache their results ... avoid outputting array properties in Blueprint pure functions.
  - BlueprintAuthorityOnly: only executes from Blueprint on a machine with network authority. BlueprintCosmetic: will not run on dedicated servers.
  - CallInEditor: button in Details panel. CustomThunk: UHT will not produce a thunk; user provides via DECLARE_FUNCTION/DEFINE_FUNCTION. Exec: console.
  - Server / Client: executed on server / owning client; implementation in `_Implementation`. NetMulticast: executed locally on server and replicated to all clients. Reliable / Unreliable: only with Client or Server. WithValidation: adds `_Validate` returning bool.
- Meta: DevelopmentOnly, Latent/LatentInfo, WorldContext, DeprecatedFunction, ExpandEnumAsExecs, BlueprintInternalUseOnly, BlueprintProtected, etc. Metadata only exists in the editor.