An attribute is a special kind of ref class that can be prepended in square brackets to Windows Runtime types and methods to specify certain behaviors in metadata creation. Several predefined attributes—for example, Windows::Foundation::Metadata::WebHostHidden—are commonly used in C++/CX code. This example shows how the attribute is applied to a class:
[Windows::Foundation::Metadata::WebHostHidden] public ref class MyClass : Windows::UI::Xaml::DependencyObject {};
You can also define custom attributes. Custom attributes must conform to these Windows Runtime rules:
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Custom attributes can contain only public fields.
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Custom attribute fields can be initialized when the attribute is applied to a class.
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A field may be one of these types:
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int32 (int)
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uint32 (unsigned int)
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bool
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Platform::String^
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Windows::Foundation::HResult
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Platform::Type^
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public enum class (includes user-defined enums)
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The next example shows how to define a custom attribute and then initialize it when you use it.
[Windows::Foundation::Metadata::WebHostHiddenAttribute]
public ref class MyCustomAttribute sealed : Platform::Metadata::Attribute {
public:
int Num;
Platform::String^ Msg;
};
[MyCustomAttribute(Num=5, Msg="Hello")]
public ref class Class1 sealed
{
public:
Class1();
};
