40 lines
1.4 KiB
Markdown
40 lines
1.4 KiB
Markdown
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# NoClear
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- **功能描述：** 指定该属性的编辑选项中不出现Clear按钮，不允许置null。
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- **元数据类型：** bool
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- **引擎模块：** DetailsPanel, Editor
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- **限制类型：** 引用类型
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- **作用机制：** 在PropertyFlags中加入[CPF_NoClear](../../../../Flags/EPropertyFlags/CPF_NoClear.md)
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- **常用程度：** ★★★
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指定该属性的编辑选项中不出现Clear按钮。
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作用是阻止用户在编辑器面板上将此Object引用设为null。但其实也可用在其他表示一个引用类型的结构上，比如FPrimaryAssetId，FInstancedStruct，FDataRegistryType等。
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## 示例代码：
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```cpp
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UPROPERTY(EditAnywhere, Category = Object)
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class UMyClass_Default* MyObject_Normal;
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//PropertyFlags: CPF_Edit | CPF_ZeroConstructor | CPF_NoClear | CPF_NoDestructor | CPF_HasGetValueTypeHash | CPF_NativeAccessSpecifierPublic
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UPROPERTY(EditAnywhere, NoClear, Category = Object)
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class UMyClass_Default* MyObject_NoClear;
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//构造函数赋值：
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MyObject_Normal = CreateDefaultSubobject<UMyClass_Default>("MyObject_Normal");
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MyObject_NoClear = CreateDefaultSubobject<UMyClass_Default>("MyObject_NoClear");
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```
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## 示例效果：
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## 原理：
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CPF_NoClear在引擎里有挺多使用。
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```cpp
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const bool bAllowClear = !StructPropertyHandle->GetMetaDataProperty()->HasAnyPropertyFlags(CPF_NoClear);
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```
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