Introduction

This tiddler describes the different ways in which procedures, functions and macros can be called. See Call Syntax for a formal description of the syntax.

Call Transclusion Shortcut

To perform a call, place <<double angle brackets>> around the callee name and any parameter values.

<<my-procedure param="This is the parameter value">>

By default, parameters are interpreted as being in the same order as in the definition. A parameter value can be labelled with its name and an equals sign to allow them to be listed in a different order.

If no value is specified for a parameter, the default value given for that parameter in the procedure definition, function definition or macro definition is used instead. (If no default value was defined, the parameter is blank).

Each parameter value can be enclosed in 'single quotes', "double quotes", """triple double quotes""" or [[double square brackets]]. Triple double quotes allow a value to contain almost anything. If a value contains no spaces or single or double quotes, it requires no delimiters. Substituted Attribute Values enclosed in single or triple back quotes are also supported.

See the discussion about parser modes

Calls with $transclude Widget

The shortcut syntax expands to the $transclude widget with the $variable attribute specifying the name of the procedure to transclude.

<$transclude $variable="my-procedure" param="This is the parameter value"/>

The widget itself offers greater flexibility than the shortcut syntax, including the ability to override it with a custom widget.

Assigning Results of Calls to Attribute Values

The text returned from a call can be directly assigned to an attribute of a widget or HTML element. The result of the call is not wikified, which means that parameter handling does not take place.

<div class=<<myclasses>>>
...
</div>

Using Calls in Filters

Calls can be used in filters. The text is not wikified which again means that the parameters will be ignored.

<$list filter="[<my-procedure>]">
...
</$list>