New in v5.3.0 The $parameters widget is used within transcluded content to declare the parameters to be made available to the $transclude widget.

There are shortcuts for common scenarios that can often make it unnecessary to use the $parameters widget directly:

• the Pragma: \parameters
• the Pragma: \procedure for declaring procedure
• the Pragma: \widget for declaring custom widgets

The $parameters widget must be used directly in the following situations:

• When the default value of a parameter must be computed dynamically
• When the $depth attribute is used to retrieve parameters from a parent transclusion (see below)

Content and Attributes

The content of the $parameters widget is the scope within which the values of the parameters can be accessed as ordinary variables.

$depth Attribute

By default, the $parameters widget retrieves parameters from the immediate parent transclusion. The $depth attribute permits access to the parameters of parent transclusions by specifying an index to the parent to be inspected ("1" is the immediate parent, "2" is the parent of that parent, etc.). This is useful in some situations where an intervening transclusion prevents immediate access to desired parameters.

$parseMode, $parseTreeNodes, $slotFillParseTreeNodes and $params Attributes

These attributes provide low level access to the contents of the transcluding widget:

• The $params attribute provides access to the raw parameters provided to the transcluding widget. Represented in JSON as an object with keys of the parameter names and values of the corresponding parameter values
• The $parseMode attribute contains block or inline to indicate whether the contents was parsed in block or inline mode
• The $parseTreeNodes attribute provides access to the raw parse tree nodes that represent the contents of the transcluding widget. Represented in JSON as an array of parse tree nodes
• The $slotFillParseTreeNodes attribute provides access to the raw parse tree nodes corresponding to the filled slots within the contents of the transcluding widget. Represented in JSON as an object with keys of the slot name and values being an array of parse tree nodes

Examples

Example i: Shows transclusion of Sample Tiddler Template. The template tiddler has two parameters name and age and here their default values are used.

<$transclude $tiddler="Sample Tiddler Template" />

Example ii: Shows, another transclusion of Sample Tiddler Template, here the value of age is passed, but name uses its default value.

<$transclude $tiddler="Sample Tiddler Template" age=33/>

Example iii: Shows, another transclusion of Sample Tiddler Template, here the value of both name and age are passed.

<$transclude $tiddler="Sample Tiddler Template" age=45 name="Jeremy Ruston" />

In the simple form the above transclusion is equivalent to

{{Sample Tiddler Template|Jeremy Ruston|45}}

In this simple form, parameters passed by position not by name. So the first value is passed to the first parameter, here name and the second value is passed to the second parameter, here age.

Remarks

1. Passing parameter by name is good practice and is recommended for clarity. So for parameterized transclusions, the use of $transclude is recommended over simple form transclusion.
2. When passing parameters value by position, you cannot pass the second parameter while the first one has not been passed.

Example iv: Here the $parameters widget is used to declare a parameter whose default value is transcluded from another tiddler.

\procedure myproc()
<$parameters name={{$:/SiteTitle}} age="21">
My name is <<name>> and my age is <<age>>.
</$parameters>
\end

<$transclude $variable="myproc" age="19"/>