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03-UnrealEngine/Gameplay/UObject/UnrealSpecifiers/Meta/Blueprint/ProhibitedInterfaces/ProhibitedInterfaces.md

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+# ProhibitedInterfaces
+
+- **功能描述：** 列出与蓝图类不兼容的接口，阻止实现
+- **使用位置：** UCLASS
+- **引擎模块：** Blueprint
+- **元数据类型：** strings="a，b，c"
+- **常用程度：** ★★
+
+## 测试代码：
+
+```cpp
+UINTERFACE(Blueprintable,MinimalAPI)
+class UMyInterface_First:public UInterface
+{
+	GENERATED_UINTERFACE_BODY()
+};
+
+class INSIDER_API IMyInterface_First
+{
+	GENERATED_IINTERFACE_BODY()
+public:
+	UFUNCTION(BlueprintCallable, BlueprintImplementableEvent)
+	void FirstFunc() const;
+};
+
+UINTERFACE(Blueprintable,MinimalAPI)
+class UMyInterface_Second:public UInterface
+{
+	GENERATED_UINTERFACE_BODY()
+};
+
+class INSIDER_API IMyInterface_Second
+{
+	GENERATED_IINTERFACE_BODY()
+public:
+	UFUNCTION(BlueprintCallable, BlueprintImplementableEvent)
+	void SecondFunc() const;
+};
+
+UCLASS(Blueprintable,meta=(ProhibitedInterfaces="UMyInterface_Second"))
+class INSIDER_API UMyClass_ProhibitedInterfaces :public UObject
+{
+	GENERATED_BODY()
+public:
+};
+```
+
+## 测试结果：
+
+发现UMyInterface_Second被阻止实现了，但是UMyInterface_First依然可以被实现
+
+![Untitled](Untitled.png)
+
+## 原理代码：
+
+可以看到在构造列表的时候，进行了过滤筛选。同时发现了.RightChop(1);的使用，因此填的接口名称，要加上U的前缀。如果UMyInterface_Second
+
+```cpp
+TSharedRef<SWidget> FBlueprintEditorUtils::ConstructBlueprintInterfaceClassPicker( const TArray< UBlueprint* >& Blueprints, const FOnClassPicked& OnPicked)
+{
+	//...
+		
+		UClass const* const ParentClass = Blueprint->ParentClass;
+		// see if the parent class has any prohibited interfaces
+		if ((ParentClass != nullptr) && ParentClass->HasMetaData(FBlueprintMetadata::MD_ProhibitedInterfaces))
+		{
+			FString const& ProhibitedList = Blueprint->ParentClass->GetMetaData(FBlueprintMetadata::MD_ProhibitedInterfaces);
+
+			TArray<FString> ProhibitedInterfaceNames;
+			ProhibitedList.ParseIntoArray(ProhibitedInterfaceNames, TEXT(","), true);
+
+			// loop over all the prohibited interfaces
+			for (int32 ExclusionIndex = 0; ExclusionIndex < ProhibitedInterfaceNames.Num(); ++ExclusionIndex)
+			{
+				ProhibitedInterfaceNames[ExclusionIndex].TrimStartInline();
+				FString const& ProhibitedInterfaceName = ProhibitedInterfaceNames[ExclusionIndex].RightChop(1);
+				UClass* ProhibitedInterface = UClass::TryFindTypeSlow<UClass>(ProhibitedInterfaceName);
+				if(ProhibitedInterface)
+				{
+					Filter->DisallowedClasses.Add(ProhibitedInterface);
+					Filter->DisallowedChildrenOfClasses.Add(ProhibitedInterface);
+				}
+			}
+		}
+
+		// Do not allow adding interfaces that are already added to the Blueprint
+		TArray<UClass*> InterfaceClasses;
+		FindImplementedInterfaces(Blueprint, true, InterfaceClasses);
+		for(UClass* InterfaceClass : InterfaceClasses)
+		{
+			Filter->DisallowedClasses.Add(InterfaceClass);
+		}
+
+		// Include a class viewer filter for imported namespaces if the class picker is being hosted in an editor context
+		TSharedPtr<IToolkit> AssetEditor = FToolkitManager::Get().FindEditorForAsset(Blueprint);
+		if (AssetEditor.IsValid() && AssetEditor->IsBlueprintEditor())
+		{
+			TSharedPtr<IBlueprintEditor> BlueprintEditor = StaticCastSharedPtr<IBlueprintEditor>(AssetEditor);
+			TSharedPtr<IClassViewerFilter> ImportedClassViewerFilter = BlueprintEditor->GetImportedClassViewerFilter();
+			if (ImportedClassViewerFilter.IsValid())
+			{
+				Options.ClassFilters.AddUnique(ImportedClassViewerFilter.ToSharedRef());
+			}
+		}
+	}
+
+	// never allow parenting to children of itself
+	for (UClass*  BPClass : BlueprintClasses)
+	{
+		Filter->DisallowedChildrenOfClasses.Add(BPClass);
+	}
+
+	return FModuleManager::LoadModuleChecked<FClassViewerModule>("ClassViewer").CreateClassViewer(Options, OnPicked);
+}
+```