F4.UPARAM

Baba我遇到困难了！

怎么了？

这里的UPARAM是啥啊？

	UFUNCTION(BlueprintCallable, BlueprintCosmetic, Category = "Global UI Extensions")
	static UCommonActivatableWidget* PushContentToLayer_ForPlayer(const ULocalPlayer* LocalPlayer, UPARAM(meta = (Categories = "UI.Layer")) FGameplayTag LayerName, UPARAM(meta = (AllowAbstract = false)) TSubclassOf<UCommonActivatableWidget> WidgetClass);

UPARAM

UPARAM 是用于更改函数参数行为的宏。

注

UPARAM(DisplayName="abc")

允许重命名函数中的参数。

UFUNCTION(BlueprintCallable)
void TestFun(
  UPARAM(DisplayName = "Test (floatname)") float Test,

注

UPARAM(ref)

修改输入输出

默认情况下，一个使用引用传递参数的 BlueprintCallable 函数会将该参数作为输出引脚（返回值）而不是输入引脚暴露。可以通过使用 UPARAM(ref) 宏来改变这种行为。

UFUNCTION(BlueprintCallable)
void FillDogInfo(FDogInfo& OutResult);

UFUNCTION(BlueprintCallable)
void UseAndFillDogInfo(
    UPARAM(ref) FDogInfo& SearchParams);

UFUNCTION(BlueprintCallable)
void UseDogInfo(const FDogInfo& SearchParams);

注

UPARAM(meta=(Categories)

限制 Gameplay 标签

如果没有现在分组，Gametag会显示所有标签。

加上UPARAM则可以直接限制到分类。

	UFUNCTION(BlueprintCallable, BlueprintCosmetic, Category = "Global UI Extensions")
	static UCommonActivatableWidget* PushContentToLayer_ForPlayer(const ULocalPlayer* LocalPlayer, UPARAM(meta = (Categories = "UI.Layer")) FGameplayTag LayerName, UPARAM(meta = (AllowAbstract = false)) TSubclassOf<UCommonActivatableWidget> WidgetClass);

注

UPARAM(meta=(AllowAbstract=true))

允许抽象选择类

UFUNCTION(BlueprintCallable, Category = "Composure", meta = (DeterminesOutputType = "OutputType"))
UCompositingElementOutput* FindOutputPass(UPARAM(meta = (AllowAbstract = "false"))TSubclassOf<UCompositingElementOutput> OutputType);

参考

https://unrealcommunity.wiki/uparam-9azlt341

https://benui.ca/unreal/uparam/