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x:FactoryMethod Directive

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Specifies a method other than a constructor that a XAML processor should use to initialize an object after resolving its backing type.

XAML Attribute Usage, no x:Arguments

<object x:FactoryMethod="methodname"...>  
  ...  
</object>

XAML Attribute Usage, x:Arguments as Element(s)

<object x:FactoryMethod="methodname"...>  
  <x:Arguments>  
    oneOrMoreObjectElements  
  </x:Arguments>  
</object>

XAML Values

Value Description
methodname The string method name of a method that XAML processors call to initialize the instance specified as object. See Remarks.
oneOrMoreObjectElements One or more object elements for objects that specify factory method parameters. Order is significant; it signifies the order in which arguments should be passed to the factory method.

Remarks

If methodname is an instance method, it cannot be qualified.

Static methods as factory methods are supported. If methodname is a static method, methodname is provided as a typeName.methodName combination, where typeName names the class that defines the static factory method. typeName can be prefix-qualified if referring to a type in a mapped xmlns. typeName can be a different type than typeof(object).

The factory method must be a declared public method of the type that backs the relevant object element.

The factory method must return an instance that is assignable to the relevant object. Factory methods should never return null.

x:Arguments operates on a principle of best match for signatures of factory methods. Matching evaluates the parameter count first. If there is more than one possible match for a parameter count, parameter type is then evaluated and best match is determined. If there is still ambiguity after this phase of evaluation, XAML processor behavior is undefined.

The x:FactoryMethod element usage is not property element usage in the typical sense, because the directive markup does not reference the containing object element's type. It is expected that element usage is less common than attribute usage. x:Arguments (either attribute or element usage) can be used along with x:FactoryMethod element usage, but this is not specifically shown in the Usage sections.

x:FactoryMethod as an element must precede any other property elements, must precede any x:Arguments also provided as elements, and must precede any content/inner text/initialization text.

See also