UE4智能指针Demo代码.zip

// Fill out your copyright notice in the Description page of Project Settings. #include "MyActor.h" // Sets default values AMyActor::AMyActor() { // Set this actor to call Tick() every frame. You can turn this off to improve performance if you don't need it. PrimaryActorTick.bCanEverTick = true; } // Called when the game starts or when spawned void AMyActor::BeginPlay() { Super::BeginPlay(); MySharePtrTest(); MySharePtrTestCastToAnotherSharePtr(); MyConstSharePtrTestCastToAnotherSharePtr(); MySharePtrToShareRef(); MyShareRefTest(); MyShareRefTestCastToAnotherShareRef(); MyConstShareRefTestCastToAnotherShareRef(); MyShareRefToSharePtr(); MyWeakPtrTest(); MyWeakPtrToSharePtr(); MyWeakPtrToShareRef(); MySharedFromThisTest(); TestCrash(); } //////////////////////////////////////////////////////////////////////////SharePtr //智能指针如何使用 void AMyActor::MySharePtrTest() { m_pSharePtrBase = MakeShareable(new ClassBase()); if (m_pSharePtrBase.IsValid() || m_pSharePtrBase.Get()) { //使用nBase m_pSharePtrBase->nBase; } } //SharePtr类型转换成其他的SharePtr void AMyActor::MySharePtrTestCastToAnotherSharePtr() { //基类对象指向了派生类的成员.多态案例在这也是一样的 TSharedPtr<ClassBase> ptrbase = MakeShareable(new ClassTop()); TSharedPtr<ClassTop> ptrcast = StaticCastSharedPtr<ClassTop>(ptrbase); if (ptrcast.IsValid()) { ptrcast->MyFunc(); } } //Const SharePtr转换成其他的SharePtr void AMyActor::MyConstSharePtrTestCastToAnotherSharePtr() { //基类对象指向了派生类的成员.多态案例在这也是一样的 const TSharedPtr<ClassBase> ptrbase = MakeShareable(new ClassTop()); { //错误写法, 不能通过ConstCastSharedPtr直接转成派生类. //TSharedPtr<ClassTop> ptrcast = ConstCastSharedPtr<ClassTop>(ptrbase); } { //正确写法1 //先通过ConstCastSharedPtr转成非const的基类 TSharedPtr<ClassBase> ptrcast = ConstCastSharedPtr<ClassBase>(ptrbase); //再通过StaticCastSharedPtr转换 TSharedPtr<ClassTop> ptrcast2 = StaticCastSharedPtr<ClassTop>(ptrcast); if (ptrcast2.IsValid()) { ptrcast2->MyFunc(); } } { //正确写法2 //直接通过StaticCastSharedPtr转换 TSharedPtr<ClassTop> ptrcast = StaticCastSharedPtr<ClassTop>(ptrbase); if (ptrcast.IsValid()) { ptrcast->MyFunc(); } } } //SharePtr类型转换成ShareRef类型 void AMyActor::MySharePtrToShareRef() { TSharedPtr<ClassBase> ptr = MakeShareable<ClassBase>(new ClassTop()); if (ptr.IsValid()) { TSharedRef<ClassBase> ref = ptr.ToSharedRef(); } } //////////////////////////////////////////////////////////////////////////ShareRef //SharePtr如何使用 void AMyActor::MyShareRefTest() { //TSharedRef没有IsValid方法, 因为它一直是有效的 TSharedRef<ClassBase> ref = MakeShareable(new ClassTop()); ref->nBase; } //ShareRef类型转换成其他的ShareRef void AMyActor::MyShareRefTestCastToAnotherShareRef() { //TSharedRef没有IsValid方法, 因为它一直是有效的 TSharedRef<ClassBase> ref = MakeShareable(new ClassTop()); TSharedRef<ClassTop> refCast = StaticCastSharedRef<ClassTop>(ref); refCast->MyFunc(); } //Const ShareRef转换成其他的ShareRef void AMyActor::MyConstShareRefTestCastToAnotherShareRef() { //TSharedRef没有IsValid方法, 因为它一直是有效的 const TSharedRef<ClassBase> ref = MakeShareable(new ClassTop()); { //错误写法, 不能通过ConstCastSharedRef直接转成派生类. //TSharedRef<ClassTop> refcast1 = ConstCastSharedRef<ClassTop>(ref); } { //正确写法1, 先通过ConstCastSharedRef转换城非Const的基类 TSharedRef<ClassBase> refcast1 = ConstCastSharedRef<ClassBase>(ref); //再通过StaticCastSharedRef转换 TSharedRef<ClassTop> refcast2 = StaticCastSharedRef<ClassTop>(refcast1); refcast2->MyFunc(); } { //正确写法2 //直接通过StaticCastSharedRef转换 TSharedPtr<ClassTop> refcast = StaticCastSharedRef<ClassTop>(ref); if (refcast.IsValid()) { refcast->MyFunc(); } } } //ShareRef类型转换成SharePtr类型 void AMyActor::MyShareRefToSharePtr() { TSharedRef<ClassBase> ref = MakeShareable(new ClassTop()); TSharedPtr<ClassBase> ptr = ref; } //////////////////////////////////////////////////////////////////////////TWeakPtr //TWeakPtr如何使用 void AMyActor::MyWeakPtrTest() { TSharedPtr<ClassBase> ptr = MakeShareable(new ClassTop()); //通过SharePtr初始化TWeakPtr TWeakPtr<ClassBase> WeakPtr = ptr; TWeakPtr<ClassBase> WeakPtr2(ptr); //通过ShareRef初始化TWeakPtr TSharedRef<ClassBase> ref = ptr.ToSharedRef(); TWeakPtr<ClassBase> WeakPtr3 = ref; TWeakPtr<ClassBase> WeakPtr4(ref); } //TWeakPtr如何转换成SharePtr void AMyActor::MyWeakPtrToSharePtr() { TSharedPtr<ClassBase> ptr = MakeShareable(new ClassTop()); //通过SharePtr初始化TWeakPtr TWeakPtr<ClassBase> WeakPtr = ptr; //利用WeakPtr的.Pin()函数将WeakPtr转成SharedPtr TSharedPtr<ClassBase> WeakPtrToSharePtrObj = WeakPtr.Pin(); if (WeakPtrToSharePtrObj.IsValid()) { //tdo smth... } } //TWeakPtr如何转换成ShareRef void AMyActor::MyWeakPtrToShareRef() { TSharedPtr<ClassBase> ptr = MakeShareable(new ClassTop()); //通过SharePtr初始化TWeakPtr TWeakPtr<ClassBase> WeakPtr = ptr; //利用WeakPtr的.Pin()函数将WeakPtr转成SharedPtr TSharedPtr<ClassBase> WeakPtrToSharePtrObj = WeakPtr.Pin(); if (WeakPtrToSharePtrObj.IsValid()) { //利用TSharedPtr的ToSharedRef()函数将TSharedPtr转换成TSharedRef TSharedRef<ClassBase> ref = WeakPtrToSharePtrObj.ToSharedRef(); } } //////////////////////////////////////////////////////////////////////////TSharedFromThis //如何使用继承自TSharedFromThis的类 void AMyActor::MySharedFromThisTest() { TSharedPtr<ClassTop> ptr = MakeShareable(new ClassTop()); if (ptr.IsValid()) { //我们通过.Get()将TSharedPtr转换成C++ 原生指针 ClassTop* pOriginPtr = ptr.Get(); //现在我们想将pOriginPtr这个原生C++指针怎么转回智能指针呢？ { //错误的用法, 也能这么用, 但是不建议 //TSharedPtr<ClassTop> ptr = MakeShareable(pOriginPtr); //错误的用法, AsShared()不能用派生类接 //TSharedPtr<ClassTop> ptr22 = pOriginPtr->AsShared(); } { //正确的用法, AsShared()不能用基类接(基类指的是你继承自TSharedFromThis的那个类) TSharedPtr<ClassBase> ptr2 = pOriginPtr->AsShared(); TSharedPtr<ClassTop> ptr3 = StaticCastSharedPtr<ClassTop>(ptr2); if (ptr3.IsValid()) { ptr3->MyFunc(); } } } }