<parameter> element

`<parameter>` element
	Appendix C. Tapestry Specification DTDs

`<parameter>` element

Appears in: <component-specification>

Defines a formal parameter of a component. Parameters may be connected (in, form or auto) or unconnected (custom). If a parameter is connected, but the class does not provide the property (or does, but the accessors are abstract), then the framework will create and use a subclass that contains the implementation of the necessary property.

For auto parameters, the framework will create a synthetic property as a wrapper around the binding. Reading the property will read the value from the binding and updating the property will update the binding value. auto may only be used with required parameters. auto is less efficient than in, but can be used even when the component is not rendering.

Figure C.24. <parameter> Attributes

Name	Type	Required ?	Default Value	Description
name	string	yes		The name of the parameter, which must be a valid Java identifier.
type	scalar name, or class name	no		Required for connected parameters. Specifies the type of the JavaBean property that a connected parameter writes and reads. The property must match this exact value, which can be a fully specified class name, or the name of a scalar Java type.
required	`yes\|no`	no	`no`	If `yes`, then the parameter must be bound (though it is possible that the binding's value will still be null).
property-name	string	no		For connected parameters only; allows the name of the property to differ from the name of the parameter. If not specified, the property name will be the same as the parameter name.
direction	`in\|form\|auto\|custom`	no	`custom`	Identifies the semantics of how the parameter is used by the component. `custom`, the default, means the component explicitly controls reading and writing values through the binding. `in` means the property is set from the parameter before the component renders, and is reset back to default value after the component renders. `form` means that the property is set from the parameter when the component renders (as with `in`). When the form is submitted, the value is read from the property and used to set the binding value after the component rewinds. `auto` creates a synthetic property that works with the binding to read and update. `auto` parameters must be required, but can be used even when the component is not rendering.
default-value	OGNL expression	no		Specifies the default value for the parameter, if the parameter is not bound.


`<page-specification>` element		`<private-asset>` element