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MarkupExtension::ProvideValue Method

When implemented in a derived class, returns an object that is provided as the value of the target property for this markup extension.

Namespace:  System.Windows.Markup
Assembly:  System.Xaml (in System.Xaml.dll)

virtual Object^ ProvideValue(
	IServiceProvider^ serviceProvider
) abstract


Type: System::IServiceProvider
A service provider helper that can provide services for the markup extension.

Return Value

Type: System::Object
The object value to set on the property where the extension is applied.

When a XAML processor processes a type node and member value that is a markup extension, it invokes the ProvideValue method of that markup extension and writes the result into the object graph or serialization stream. The XAML object writer passes service context to each such implementation through the serviceProvider parameter.

See "Notes to Implementers" section for more information on how to implement ProvideValue in a custom markup extension.

WPF Usage Notes

Important noteImportant

WPF classes that have specific interactions with markup set operations should not rely on IReceiveMarkupExtension for a .NET Framework 4 implementation. Use XamlSetMarkupExtensionAttribute-attributed callbacks instead.

Notes to Implementers

Common services returned by the default service provider that is typically available to a custom or existing MarkupExtension implementation include the following primary services.

Potentially, implementations of ProvideValue can ignore the serviceProvider parameter. This is viable for some basic scenarios, where no context at all is required for returning a value.

In typical usage, the .NET Framework XAML Services and the implemented XAML object writers will provide a service provider to all value converter methods it invokes during XAML processing. However, for robustness, you should provide code paths for null values both for the service provider itself and for any requested service. Null values might occur if your markup extension is applied in some circumstance where the typical service support provided by a XAML parser infrastructure is not available.

For more information on available services from the XAML service provider context and how to use them, see Type Converters and Markup Extensions for XAML.

Implementations that require a certain service to return a value are expected to throw exceptions if that service is not available. The recommended exception to throw is InvalidOperationException.

You may also throw exceptions if one of the arguments that your custom markup extension needs in order to provide a value is null, is invalid for its data type, or does not contain a value that your markup extension is capable of processing. The recommended exception to throw is InvalidOperationException.

.NET Framework

Supported in: 4, 3.5, 3.0

.NET Framework Client Profile

Supported in: 4, 3.5 SP1

Windows 7, Windows Vista SP1 or later, Windows XP SP3, Windows Server 2008 (Server Core not supported), Windows Server 2008 R2 (Server Core supported with SP1 or later), Windows Server 2003 SP2

The .NET Framework does not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.