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For some USTRUCT structs within UnrealEngine, type traits TStructOpsTypeTraits<T> are defined. These provide a list of bools (encapsulated in an enumeration) about the implemented capabilities of struct T.

1. What is the usage of those traits?


2. When I should define those traits for my custom USTRUCTs within my project?

*Example usage from within the Engine:

struct TStructOpsTypeTraitsBase2

{

    enum

    {

        WithZeroConstructor            = false,                         // struct can be constructed as a valid object by filling its memory footprint with zeroes.

        WithNoInitConstructor          = false,                         // struct has a constructor which takes an EForceInit parameter which will force the constructor to perform initialization, where the default constructor performs 'uninitialization'.

        WithNoDestructor               = false,                         // struct will not have its destructor called when it is destroyed.

        WithCopy                       = !TIsPODType<CPPSTRUCT>::Value, // struct can be copied via its copy assignment operator.

        // ...

    }

}

Which is used like

template<>

struct TStructOpsTypeTraits<FGameplayEffectContextHandle> : public TStructOpsTypeTraitsBase2<FGameplayEffectContextHandle>

{

    enum

    {

        WithCopy = true,        // Necessary so that TSharedPtr<FGameplayEffectContext> Data is copied around

        WithNetSerializer = true,

        WithIdenticalViaEquality = true,

    };

};