caption: Variables
created: 20141002141231992
modified: 20220909111836951
tags: WikiText
title: Variables in WikiText
type: text/vnd.tiddlywiki

See also the [[introduction to the concept of variables|Variables]].

To transclude the value of a variable, use the [[macro call syntax|Macro Calls in WikiText]] or the <<.wlink TranscludeWidget>> widget with the `$variable` attribute.

A [[macro|Macros]] snippet can contain `$(name)$` as a [[placeholder|Macro Definitions in WikiText]] for which the value of the variable of that name will be substituted.

A variable's value can be used as a [[filter parameter|Filter Parameter]], or as a [[widget attribute|Widgets in WikiText]]. The latter supports macro parameters.

!! Example: defining a variable

<$macrocall $name=".example" n="1"
eg="""<$set name=animal value=zebra>
<<animal>>
</$set>"""/>

!! Example: defining a macro

The `\define` pragma below [[defines a macro|Macros in WikiText]] called <<.var tags-of-current-tiddler>>. The macro returns the value of the tiddler's <<.field tags>> field, and can be accessed from anywhere else in the same tiddler (or in any tiddler that [[imports|ImportVariablesWidget]] it).

<$importvariables filter="$:/editions/tw5.com/macro-examples/tags-of-current-tiddler">
<$codeblock code={{$:/editions/tw5.com/macro-examples/tags-of-current-tiddler}}/>
<$macrocall $name=".example" n="2" eg="""The tags are: <<tags-of-current-tiddler>>"""/>
</$importvariables>

!! Example: using a variable as a filter parameter

This example uses the <<.olink backlinks>> [[operator|Filter Operators]] to list all tiddlers that link to this one.

<$macrocall $name=".example" n="3" eg="""<<list-links filter:"[<currentTiddler>backlinks[]]">>"""/>