114 lines
5.1 KiB
Markdown
114 lines
5.1 KiB
Markdown
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# Deprecated
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- **功能描述：** 标明该类已经弃用。
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- **引擎模块：** Development
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- **元数据类型：** bool
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- **作用机制：** 在ClassFlags添加[CLASS_Deprecated](../../../../Flags/EClassFlags/CLASS_Deprecated.md)、[CLASS_NotPlaceable](../../../../Flags/EClassFlags/CLASS_NotPlaceable.md)，在Meta添加[DeprecationMessage](../../../../Meta/Development/DeprecationMessage.md)、[DeprecatedProperty](../../../../Meta/Development/DeprecatedProperty/DeprecatedProperty.md)
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- **常用程度：★★★**
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标明该类已经弃用。
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弃用会导致：不可被创建，不可被序列化保存，在继承列表里被过滤掉。此说明符子类会继承下来，标明子类也是废弃的。标上Deprecated 的类需要在类名前加上UDEPRECATED_的显眼前缀，但是类名不会变，Actor加ADEPRECATED_，UObject加UDEPRECATED_。ClassFLags里会标上CLASS_Deprecated和CLASS_NotPlaceable。注意还是可以正常NewObject使用的。而SpawnActor会失败，报错： failed because class %s is deprecated。EditInline也都会被禁止。
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## 示例代码1：
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```cpp
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UCLASS(Blueprintable)
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class INSIDER_API UMyClass_Deprecated :public UObject
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{
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GENERATED_BODY()
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};
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//改为：
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UCLASS(Blueprintable, Deprecated)
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class INSIDER_API UDEPRECATED_MyClass_Deprecated :public UObject
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{
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GENERATED_BODY()
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};
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```
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## 示例效果1：
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依然可以NewObject。
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## 示例代码2：
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但要注意这个是UE的标记。源码里还看见很多UE_DEPRECATED宏的使用，则是在VS编译器级别的标记，会根据使用引用情况在编译的步骤中生成警告。
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```cpp
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UCLASS(Blueprintable, BlueprintType)
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class INSIDER_API UMyClass_Deprecated_Test :public UObject
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{
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GENERATED_BODY()
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public:
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UE_DEPRECATED(5.2, "MyClass_Deprecated has been deprecated, please remove it.")
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UDEPRECATED_MyClass_Deprecated* MyProperty_Deprecated;
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UE_DEPRECATED(5.2, "MyIntProperty has been deprecated, please remove it.")
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UPROPERTY(EditAnywhere, BlueprintReadWrite,meta=(DeprecatedProperty, DeprecationMessage = "MyIntProperty has been deprecated."))
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int MyIntProperty;
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UE_DEPRECATED(5.2, "MyClass_Deprecated has been deprecated, please remove it.")
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void MyFunc(UDEPRECATED_MyClass_Deprecated* obj){}
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UFUNCTION(BlueprintCallable, meta = (DeprecatedProperty, DeprecationMessage="MyVoidFunc has been deprecated."))
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void MyVoidFunc(){}
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};
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UCLASS(Blueprintable, BlueprintType)
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class INSIDER_API UMyClass_Deprecated_Usage :public UObject
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{
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GENERATED_BODY()
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public:
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void MyFunc()
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{
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UMyClass_Deprecated_Test* obj=NewObject<UMyClass_Deprecated_Test>();
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UDEPRECATED_MyClass_Deprecated* obj2 = NewObject<UDEPRECATED_MyClass_Deprecated>();
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obj->MyProperty_Deprecated= obj2;
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obj->MyProperty_Deprecated->MyFunc();
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obj->MyIntProperty++;
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obj->MyFunc(obj2);
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obj->MyVoidFunc();
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}
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};
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编译警告：
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warning C4996: 'UMyClass_Deprecated_Test::MyProperty_Deprecated': MyClass_Deprecated has been deprecated, please remove it. Please update your code to the new API before upgrading to the next release, otherwise your project will no longer compile.
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warning C4996: 'UMyClass_Deprecated_Test::MyProperty_Deprecated': MyClass_Deprecated has been deprecated, please remove it. Please update your code to the new API before upgrading to the next release, otherwise your project will no longer compile.
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warning C4996: 'UMyClass_Deprecated_Test::MyIntProperty': MyIntProperty has been deprecated, please remove it. Please update your code to the new API before upgrading to the next release, otherwise your project will no longer compile.
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warning C4996: 'UMyClass_Deprecated_Test::MyFunc': MyClass_Deprecated has been deprecated, please remove it. Please update your code to the new API before upgrading to the next release, otherwise your project will no longer compile.
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注意如果没有UE_DEPRECATED标记，则不会生成编译警告。
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UPROPERTY(EditAnywhere, BlueprintReadWrite) int MyInt2Property_DEPRECATED;
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会触发：
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warning : Member variable declaration: Deprecated property 'MyInt2Property_DEPRECATED' should not be marked as blueprint visible without having a BlueprintGetter
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warning : Member variable declaration: Deprecated property 'MyInt2Property_DEPRECATED' should not be marked as blueprint writable without having a BlueprintSetter
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warning : Member variable declaration: Deprecated property 'MyInt2Property_DEPRECATED' should not be marked as visible or editable
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因此只能改成：
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UPROPERTY() int MyInt2Property_DEPRECATED;
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```
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## 示例效果2：
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属性和函数上加上Deprecated标记后，会在BP编译的时候生成警告。注意函数是先有一个正常的函数，在BP里连接完成之后再在C++里标记DeprecatedFunction才会生成警告，否则已经Deprecated的函数是无法再在BP里调用的。
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## 原理：
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源码中有众多CLASS_Deprecated的判断，比如SpawnActor：
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```cpp
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AActor* UWorld::SpawnActor( UClass* Class, FTransform const* UserTransformPtr, const FActorSpawnParameters& SpawnParameters )
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{
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if( Class->HasAnyClassFlags(CLASS_Deprecated) )
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{
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UE_LOG(LogSpawn, Warning, TEXT("SpawnActor failed because class %s is deprecated"), *Class->GetName() );
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return NULL;
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}
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}
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```
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