caption: Calls
created: 20221007130006705
modified: 20260301030947969
tags: WikiText Procedures Functions Macros
title: Calls
type: text/vnd.tiddlywiki

!! Introduction

This tiddler describes the different ways in which [[procedures|Procedures]], [[functions|Functions]] and [[macros|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|Procedure Definitions]], [[function definition|Function Definitions]] or [[macro definition|Macro Definitions]] 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|WikiText parser mode: macro examples]]

!!! Examples

<<testcase TestCases/Calls/ProcedureStaticAttributes>>

<<testcase TestCases/Calls/ProcedureDynamicAttributes>>

!! Calls with <<.wlink TranscludeWidget>> Widget

The shortcut syntax expands to the <<.wlink TranscludeWidget>> 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|Procedure 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.

//Note that currently only literal string parameters are supported//

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