TiddlyWiki5/editions/tw5.com/tiddlers/widgets/VarsWidget.tid

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 assignement
* Variable names must be literal strings