Class LocalizeExtension

{Localize Key}: the localized string for a key, in the configuration's Culture, updated when the culture changes.

[MarkupExtensionDefaultProperty("Key")]
public sealed class LocalizeExtension : IMarkupExtension

Inherited Members: object.Equals(object)

object.Equals(object, object)

object.GetHashCode()

object.GetType()

object.ReferenceEquals(object, object)

object.ToString()

Extension Methods: PropertyReferencesExtensions.ContainsProperty(object, IPropertyReference)

Remarks

{Localize Menu.Play} is short for {Localize Key=Menu.Play}; Context= tells apart keys with the same text (gettext's msgctxt).
On a property that doesn't take text, such as Content, the string goes through the configuration's text converter, as a plain string attribute does: Content gets a TextBlock.
A missing key shows the key itself (see Localize(string, string?)).
In a style setter, the string is resolved once, when the style loads, and doesn't change with the culture: styles are shared by many elements. Templates are fine.

Gets or sets an optional context for the key, or null.

public string? Context { get; set; }

Gets or sets the key, such as Menu.Play.

public string Key { get; set; }

Computes the value the loader should use.

public object? ProvideValue(MarkupExtensionContext context)

context MarkupExtensionContext: The property being resolved, and what the loader knows about the document.

object: The value to assign, converted the same way an ordinary attribute value would be; or Unset when the extension already applied its own effect (typically by binding the property itself) and nothing further should be assigned.

MarkupException: No key is given, or the string can't be converted to the property's type.