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TiddlyWiki5/editions/tw5.com/tiddlers/widgets/VarsWidget.tid
2022-12-21 10:07:14 +00:00

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title: VarsWidget
created: 20150426115958020
modified: 20150426115958020
tags: Widgets
caption: vars
! Introduction
The <<.wid vars>> widget allows multiple variables to be set in one operation. In some situations it can result in simpler code than using the more flexible <<.wlink SetWidget>> widget. It differs from the <<.wlink LetWidget>> in that variables cannot interfere with the evaluation of other variables within the same <<.wid vars>>.
! Content and Attributes
The content of the <<.wid vars>> widget is the scope for the value assigned to the variable.
|!Attribute |!Description |
|//{attributes not starting with $}// |Each attribute name specifies a variable name. The attribute value is assigned to the variable |
Attributes will not interfere with the evaluation of other attributes. So if one attribute sets <<.attr currentTiddler>>, and another attribute uses <<.attr currentTiddler>> in its evaluation, it will use the value of <<.attr currentTiddler>> that exists outside the widget's scope.
! Examples
Consider a case where you need to set multiple variables.
Using the <<.wid vars>> widget, this situation may be handled in the following way:
```
\define helloworld() Hello world!
<$vars greeting="Hi" me={{!!title}} sentence=<<helloworld>>>
<<greeting>>! I am <<me>> and I say: <<sentence>>
</$vars>
```
In contrast, here is the same example using the <<.wid set>> widget:
```
<$set name="greeting" value="Hi" >
<$set name="me" value={{!!title}} >
<$set name="sentence" value=<<helloworld>> >
<<greeting>>! I am <<me>> and I say: <<sentence>>
</$set>
</$set>
</$set>
```
! Remarks
It should be noted that this widget differs from the <<.wid set>> widget in the following ways:
* A fallback (also known as "emptyValue") cannot be specified
* Filters cannot be used to produce a conditional variable assignment
* Variable names must be literal strings