Question

If I have the following:

struct LineChartScene::LineChartSceneImpl
{
    enum ContextMenuAction {ShowLabels, ShowPoints, SaveAsImage};
};

How can I access ShowLabels, ShowPoints etc outside LineChartScene::LineChartSceneImpl struct? I thought LineChartScene::LineChartSceneImpl::ContextMenuAction::ShowLabels would work but it doesn’t. I’m using C++, Qt Creator 2.2.1.

Answer 1

struct LineChartScene::LineChartSceneImpl
{
    enum ContextMenuAction {ShowLabels, ShowPoints, SaveAsImage};
};

use it as

LineChartScene::LineChartSceneImpl::ShowLabels

For your info, C++11 also has strong typed enums with precisely the namespace semantics you expected:

enum class Enum2 : unsigned int {Val1, Val2};

The scoping of the enumeration is also defined as the enumeration name’s scope. Using the enumerator names requires explicitly scoping. Val1 is undefined, but Enum2::Val1 is defined.

Additionally, C++11 will allow old-style enumerations to provide explicit scoping as well as the definition of the underlying type:

enum Enum3 : unsigned long {Val1 = 1, Val2};

The enumerator names are defined in the enumeration’s scope (Enum3::Val1), but for backwards compatibility, enumerator names are also placed in the enclosing scope.