44 lines
1.7 KiB
Markdown
44 lines
1.7 KiB
Markdown
|
# Required
|
||
|
|
|
||
|
|
- **功能描述：** 指定函数的参数节点必须连接提供一个值
|
||
|
|
|
||
|
|
- **元数据类型：** bool
|
||
|
|
- **引擎模块：** Blueprint, Parameter
|
||
|
|
- **作用机制：** 在PropertyFlags中加入[CPF_RequiredParm](../../../../Flags/EPropertyFlags/CPF_RequiredParm.md)
|
||
|
|
- **常用程度：** ★★
|
||
|
|
|
||
|
|
指定函数的参数节点必须连接个变量来提供一个值。
|
||
|
|
|
||
|
|
如果参数上有提供默认值，该标志依然会忽略默认值，认为还是没提供值。还是必须要连接变量。
|
||
|
|
|
||
|
|
## 测试代码：
|
||
|
|
|
||
|
|
```cpp
|
||
|
|
//PropertyFlags: CPF_Parm | CPF_ZeroConstructor | CPF_RequiredParm | CPF_NoDestructor | CPF_HasGetValueTypeHash | CPF_NativeAccessSpecifierPublic
|
||
|
|
UFUNCTION(BlueprintCallable)
|
||
|
|
FString MyFuncTestParam_RequiredObject(UPARAM(Required) UObject* objValue);
|
||
|
|
|
||
|
|
//(CPP_Default_intValue = 123, ModuleRelativePath = Function/Param/MyFunction_TestParam.h)
|
||
|
|
//PropertyFlags: CPF_Parm | CPF_ZeroConstructor | CPF_RequiredParm | CPF_IsPlainOldData | CPF_NoDestructor | CPF_HasGetValueTypeHash | CPF_NativeAccessSpecifierPublic
|
||
|
|
UFUNCTION(BlueprintCallable)
|
||
|
|
FString MyFuncTestParam_RequiredInt(UPARAM(Required) int intValue=123);
|
||
|
|
```
|
||
|
|
|
||
|
|
## 蓝图节点：
|
||
|
|
|
||
|
|
|
||
|
|
|
||
|
|
如果不连一个节点，编译时会报错：
|
||
|
|
|
||
|
|
Pin Int Value must be linked to another node (in My Func Test Param Required Int )
|
||
|
|
Pin Obj Value must be linked to another node (in My Func Test Param Required Object )
|
||
|
|
|
||
|
|
## 原理：
|
||
|
|
|
||
|
|
根据这个标记来判断。
|
||
|
|
|
||
|
|
```cpp
|
||
|
|
const bool bIsRequiredParam = Param->HasAnyPropertyFlags(CPF_RequiredParm);
|
||
|
|
// Don't let the user edit the default value if the parameter is required to be explicit.
|
||
|
|
Pin->bDefaultValueIsIgnored |= bIsRequiredParam;
|
||
|
|
```
|