Make Save System

Development Programming & Scripting C++
16

Hi Alonzo!

I’m a bit surprised with 's solution as, in C++, operator<< must return a valid object, usually the first parameter of the overloaded function, the object stream. Whether it is used in an Unreal environment or not should not change the rules of C++. :slight_smile: The empty return statement at the beginning is invalid as is yours.

This is how I would do it:



FORCEINLINE FArchive& operator<<(FArchive &Ar, UCustomSaveGame* SaveGameData )
{
    if (SaveGameData)
    {
      
        Ar << SaveGameData->NumItemsCollected;  //int32
        Ar << SaveGameData->PlayerLocation;  //FVector
        Ar << SaveGameData->ArrayOfRotationsOfTheStars; //TArray<FRotator>
    }
    
    return Ar;
}

This permits streams like the one above to been daisy-chained as each << operator feeds on the output of its predecessor. The return value is what permits the archive to work as a stream. The code above is the same as:



Ar << SaveGameData->NumItemsCollected << SaveGameData->PlayerLocation << SaveGameData->ArrayOfRotationsOfTheStars;

So a return value is mandatory. If you test the validity of the pointer and the pointer is NULL, like in the code above, the stream is unaffected; nothing is added to Ar. It is simply passed along the next value to stream.

My problem with this code is that if a test fails then there is no way for a reader function to know whether the content was stored in the first place. I prefer passing objects by reference without any pointer conversion or testing at all.



FORCEINLINE FArchive& operator<<(FArchive &Ar, UCustomSaveGame& SaveGameData)
{
    Ar << SaveGameData.NumItemsCollected;  //int32
    Ar << SaveGameData.PlayerLocation;  //FVector
    Ar << SaveGameData.ArrayOfRotationsOfTheStars; //TArray<FRotator>
 
    return Ar;
}

But do not use **const ** on the reference because Ar does not use const itself and it wouldn’t help the reader function, of course.