FGMPTypedAddr

FGMPTypedAddr

One argument, type-erased: an address, plus its type name when the build keeps type names.

Declared in Plugins/GMP/Source/GMP/GMP/GMPStruct.h:127

USTRUCT(BlueprintType, meta = (HiddenByDefault = true))
struct GMP_API FGMPTypedAddr
{
    GENERATED_BODY()
public:
    UPROPERTY()
    uint64 Value = 0;

#if GMP_WITH_TYPENAME
    FName TypeName;
#endif
};

Fields

Field	Always present	Meaning
Value	yes	The argument's address, converted to an integer by HorribleFromAddr. Not a copy of the value — the argument still lives on the sender's stack for the duration of the dispatch.
TypeName	only under GMP_WITH_TYPENAME	The reflected type name from Class2Name, used for validation and by script backends.

GMP_WITH_TYPENAME is GMP_WITH_DYNAMIC_TYPE_CHECK || GMP_WITH_DYNAMIC_CALL_CHECK || GMP_WITH_TYPE_INFO_EXTENSION (GMPMacros.h), which is on in Editor and Development and off in Shipping.

So in Shipping the struct is layout-identical to a bare uint64, and an argument array really is nothing but an array of addresses.

Constructors

FGMPTypedAddr(const void* Addr, FName InName);
FGMPTypedAddr(const void* Addr, const FProperty* Prop);   // name via Reflection::GetPropertyName
FGMPTypedAddr(const void* Addr);                          // no name

The FProperty* form is the one to use when you are bridging from reflection — see Class2Name.

Lifetime — read this before storing one

The struct holds an address, not a value. It is valid for the duration of the dispatch and no longer. Capturing an FGMPTypedAddr and reading it after the send returns is a use-after-free.

Anything that has to outlive the dispatch must copy the value out. That is exactly what StoreObjectMessage does, and why it packs into an FGMPStructUnion rather than keeping the address.

Where you meet it

Listeners written in C++ never see this type — the thunk decodes the array back into typed parameters before your lambda runs. You meet it when writing a backend or a bridge, where the callback signature is the raw one:

void (*)(void* Self, const FGMPTypedAddr* Params, const FGMPExtra* Extra);

Params is an array of Extra->Size entries. See FGMPRawSig.

Type names travel on two channels

Do not assume TypeName is the only source:

Channel	Available	Granularity
FGMPTypedAddr::TypeName	Editor / Development only	per argument
FGMPExtra::TypeNames	always	one static table per signature

Code that must work in Shipping reads FGMPExtra::TypeNames together with Size.

See also

FGMPExtra · FGMPRawSig · FMessageBody · Class2Name · Build switches