unreal3对象属性自动从配置文件中加载的机制

class HNet extends Object
    config(game)
    native(net);

//var globalconfig string host;
var config string host; 

function test() { `Log("HNet test, host is:"@host); }

class HHttp extends HNet
    config(Net)
    ;
    
function test()
{
    `Log("HHttp test, host is:"@host);
}

#define CPF_Config       DECLARE_UINT64(0x0000000000004000) // Property should be loaded/saved as permanent profile.
#define CPF_GlobalConfig DECLARE_UINT64(0x0000000000040000) // Load config from base class, not subclass.

        FToken Specifier;
        GetToken(Specifier);
        if( Specifier.Matches(NAME_Const) )
        {
            Flags      |= CPF_Const;
            IsVariable  = TRUE;
        }
        else if( Specifier.Matches(NAME_Config) )
        {
            Flags      |= CPF_Config;
            IsVariable  = TRUE;
        }
        else if( Specifier.Matches(NAME_GlobalConfig) )
        {
            Flags      |= CPF_GlobalConfig | CPF_Config;
            IsVariable  = TRUE;
        }

UField*　　　　　　　　　　Children
UObject*　　　　　　　　　 ClassDefaultObject

//
// An UnrealScript variable.
//
class UProperty : public UField
{
    DECLARE_ABSTRACT_CASTED_CLASS_INTRINSIC(UProperty,UField,0,Core,CASTCLASS_UProperty)
    DECLARE_WITHIN(UField)

    // Persistent variables.
    INT            ArrayDim;
    INT            ElementSize;
    QWORD        PropertyFlags;
    WORD            RepOffset;
    WORD            RepIndex;

    for ( UProperty* Property = ConfigClass->PropertyLink; Property; Property = Property->PropertyLinkNext )
    {
        
        const UBOOL bGlobalConfig = (Property->PropertyFlags&CPF_GlobalConfig) != 0;
        UClass* OwnerClass = Property->GetOwnerClass();

        UClass* BaseClass = bGlobalConfig ? OwnerClass : ConfigClass;
        if ( !bPerObject )
        {
            ClassSection = BaseClass->GetPathName();
        }

        // globalconfig properties should always use the owning class‘s config file
        // specifying a value for InFilename will override this behavior (as it does with normal properties)
        const FString& PropFileName = (bGlobalConfig && InFilename == NULL) ? OwnerClass->GetConfigName() : Filename;

        FString Key = Property->GetName();
        debugfSuppressed(NAME_DevSave, TEXT("   Loading value for %s from [%s]"), *Key, *ClassSection);
        UArrayProperty* Array = Cast<UArrayProperty>( Property );
        if( Array == NULL )
        {
            for( INT i=0; i<Property->ArrayDim; i++ )
            {
                if( Property->ArrayDim!=1 )
                {
                    Key = FString::Printf(TEXT("%s[%i]"), *Property->GetName(), i);
                }

                FString Value;
                if( GConfig->GetString( *ClassSection, *Key, Value, *PropFileName ) )
                {
                    if (Property->ImportText(*Value, (BYTE*)this + Property->Offset + i*Property->ElementSize, PPF_ConfigOnly, this) == NULL)
                    {
                        // this should be an error as the properties from the .ini / .int file are not correctly being read in and probably are affecting things in subtle ways
                        warnf(NAME_Error, TEXT("LoadConfig (%s): import failed for %s in: %s"), *GetPathName(), *Property->GetName(), *Value);
                    }
　　　　　　　　　 }
　　　　　　  }
　　　　  }
　　　　  else
　　　　　　　……
　　  ……
　　  }
}

// Construct anything required.
    if( DefaultsClass && DefaultData )
    {
        for( UProperty* P=DefaultsClass->ConstructorLink; P; P=P->ConstructorLinkNext )
        {
            if( P->Offset < DefaultsCount )
            {
                // skip if SourceOwnerObject != NULL and this is a transient property - in this
                // situation, the new value for the property has already been copied from the class defaults
                // in the block of code above
                if ( SubobjectRoot == NULL || !P->HasAnyPropertyFlags(CPF_Transient|CPF_DuplicateTransient) )
                {
                    // the heap memory allocated at this address is owned the source object, so
                    // zero out the existing data so that the UProperty code doesn‘t attempt to
                    // de-allocate it before allocating the memory for the new value
                    appMemzero( Data + P->Offset, P->GetSize() );//bad for bools, but not a real problem because they aren‘t constructed!!
                    P->CopyCompleteValue( Data + P->Offset, DefaultData + P->Offset, SubobjectRoot ? SubobjectRoot : DestObject, DestObject, InstanceGraph );
                }
            }
        }
    }