UE4中的反射机制

UNREAL4 PROPERTY SYSTEM

参见 https://www.unrealengine.com/blog/unreal-property-system-reflection

//////////////////////////////////////////////////////////////////////////
// Base class for mobile units (soldiers)
#include "StrategyTypes.h"
#include "StrategyChar.generated.h"
 
UCLASS(Abstract)
class AStrategyChar : public ACharacter, public IStrategyTeamInterface
{
GENERATED_UCLASS_BODY()
 
/** How many resources this pawn is worth when it dies. */
UPROPERTY(EditAnywhere, Category=Pawn)
int32 ResourcesToGather;
 
/** set attachment for weapon slot */
UFUNCTION(BlueprintCallable, Category=Attachment)
void SetWeaponAttachment(class UStrategyAttachment* Weapon);
 
UFUNCTION(BlueprintCallable, Category=Attachment)
bool IsWeaponAttached();
 
protected:
/** melee anim */
UPROPERTY(EditDefaultsOnly, Category=Pawn)
UAnimMontage* MeleeAnim;
 
/** Armor attachment slot */
UPROPERTY()
UStrategyAttachment* ArmorSlot;
 
/** team number */
uint8 MyTeamNum;
[more code omitted]
};

USING REFLECTION DATA

UField
UStruct
UClass (C++ class)
UScriptStruct (C++ struct)
UFunction (C++ function)
UEnum (C++ enumeration)
UProperty (C++ member variable or function parameter)
(Many subclasses for different types)

To iterate over all members of a UStruct, use a TFieldIterator:

 for (TFieldIterator<UProperty> PropIt(GetClass()); PropIt; ++PropIt)
    {
        UProperty* Property = *PropIt;
        UE_LOG(YourLog, Warning, TEXT("get property:%s"), *(PropIt->GetFName()).ToString());
        // Do something with the property
    }

Object iterators are a very useful tool to iterate over all instances of a particular UObject type and its subclasses.

for (TObjectIterator<UObject> It; It; ++It)
    {
        UObject* CurrentObject = *It;
        UE_LOG(YourLog, Log, TEXT("Found UObject named: %s"), *CurrentObject->GetName());
    }

ActorIterator

APlayerController* MyPC = GetMyPlayerControllerFromSomewhere();
UWorld* World = MyPC->GetWorld();

// Like object iterators, you can provide a specific class to get only objects that are
// or derive from that class
for (TActorIterator<AEnemy> It(World); It; ++It)
{
    // ...
}