TiddlyWiki5/editions/tw5.com/tiddlers/wikitext/Variables in WikiText.tid

caption: Variables
created: 20141002141231992
modified: 20150107121000000
tags: WikiText
title: Variables in WikiText
type: text/vnd.tiddlywiki

\define tags() {{!!tags}}

[[Variables]] contain values. They are available within the scope of the [[widget|Widgets]] in which they are defined, as well as all child widgets in the widget tree.

!!Defining Variables

Variables are defined by...

; [[Macros|Macros in WikiText]]
: in fact, variables are macro shorthands (see example below)
; SetWidget
: sets a variable to a value
; ListWidget
: sets list-item and iterator variabes
; TiddlyWiki
: in the core and core templates

!!Using Variables

Variables are used via...

; shorthand
:`<<variableName>>`
; variable substitution within [[macros|Macros]]
:`$(variableName)$`
; as variable operands in [[filter expressions|Introduction to Filters]]
: `[operator<variableName>]`
; in [[widgets|Widgets]]
: internally, or as widget attributes
: `<$edit tiddler=<<currentTiddler>>/>`

!! Examples

''defining a variable via SetWidget''

```
<$set name=foo value=bar>
<<foo>>
</$set>
```

<<<
<$set name=foo value=bar>
<<foo>>
</$set>
<<<

''a variable is a macro''

Below, the `\define` pragma at the beginning of a tiddler [[defines the macro|Macros in WikiText]] `<<tags>>`, valid in the scope of the CurrentTiddler, returning the value of the standard `tags` field.

```
\define tags() {{!!tags}}

<<tags>>
```

<<<
<<tags>>
<<<

''using a filter variable to get all incoming links''

Using the [[backlinks|FilterOperator: backlinks]] [[filter operator|FilterOperators]] to get all tiddlers linking to this one...

```
<<list-links filter:"[<currentTiddler>backlinks[]]">>
```

<<<
<<list-links filter:"[<currentTiddler>backlinks[]]">>
<<<