C++ 如何减少函数模板专门化?
我正试图使用他们的反射系统编写一个在UE4中使用的属性验证器。 我首先想到的是:C++ 如何减少函数模板专门化?,c++,templates,template-specialization,C++,Templates,Template Specialization,我正试图使用他们的反射系统编写一个在UE4中使用的属性验证器。 我首先想到的是: class FDataValidator { public: FDataValidator( UObject & object, TArray< FText > & validation_errors ) : Object( object ), ValidationResult( validation_errors.Num() == 0 ? EDa
class FDataValidator
{
public:
FDataValidator( UObject & object, TArray< FText > & validation_errors ) :
Object( object ),
ValidationResult( validation_errors.Num() == 0 ? EDataValidationResult::Valid : EDataValidationResult::Invalid ),
ObjectClass( Object.GetClass() ),
ValidationErrors( validation_errors )
{}
template < class _TYPE_ >
FDataValidator & GreaterThan( const FName property_name, const _TYPE_ value );
EDataValidationResult Result() const
{
return ValidationResult;
}
private:
template < class _PROPERTY_TYPE_, class _VALUE_TYPE_, class _COMPARATOR_TYPE_ >
FDataValidator & CompareProperty( const FName property_name, const _VALUE_TYPE_ value, _COMPARATOR_TYPE_ comparator = _COMPARATOR_TYPE_() )
{
if ( auto * property = GetTypedProperty< _PROPERTY_TYPE_ >( property_name ) )
{
const auto property_value = property->GetPropertyValue_InContainer( &Object );
if ( !comparator( property_value, value ) )
{
AddError( FText::FromString( FString::Printf( TEXT( "%s must be greater than %f" ), *property_name.ToString(), value ) ) );
}
}
return *this;
}
template < class _PROPERTY_TYPE_ >
_PROPERTY_TYPE_ * GetTypedProperty( const FName property_name )
{
if ( auto * property = ObjectClass->FindPropertyByName( property_name ) )
{
if ( auto * typed_property = Cast< _PROPERTY_TYPE_ >( property ) )
{
return typed_property;
}
}
return nullptr;
}
void AddError( FText text )
{
ValidationErrors.Emplace( text );
ValidationResult = EDataValidationResult::Invalid;
}
UObject & Object;
EDataValidationResult ValidationResult;
UClass * ObjectClass;
TArray< FText > & ValidationErrors;
};
template <>
FDataValidator & FDataValidator::GreaterThan< float >( const FName property_name, const float value )
{
return CompareProperty< UFloatProperty, float, std::greater< float > >( property_name, value );
}
template <>
FDataValidator & FDataValidator::GreaterThan< int >( const FName property_name, const int value )
{
return CompareProperty< UIntProperty, int, std::greater< int > >( property_name, value );
}
感谢
UFloatProperty
和其他数字类型似乎来自TProperty\u numeric
。
因此,类似这样的解决方案可能是:
template <typename T>
FDataValidator& FDataValidator::GreaterThan<T>(const FName property_name, const T value)
{
return CompareProperty<TProperty_Numeric<T>, T, std::greater<T>>(property_name, value);
}
模板
FDataValidator&FDataValidator::GreaterThan(常量FName属性名称,常量T值)
{
返回CompareProperty(属性名称、值);
}
template <typename T>
FDataValidator& FDataValidator::GreaterThan<T>(const FName property_name, const T value)
{
return CompareProperty<TProperty_Numeric<T>, T, std::greater<T>>(property_name, value);
}