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2bfe522b72
* $let widget added and tested * Documentation for $let, doc improvements for $vars * let properly avoids refreshing when possible * $let Changes as recommended by others * Removed superfluous super method call Also improved $let test
53 lines
1.9 KiB
Plaintext
53 lines
1.9 KiB
Plaintext
title: VarsWidget
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created: 20150426115958020
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modified: 20150426115958020
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tags: Widgets
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caption: vars
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! Introduction
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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>>.
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! Content and Attributes
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The content of the <<.wid vars>> widget is the scope for the value assigned to the variable.
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|!Attribute |!Description |
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|//{attributes not starting with $}// |Each attribute name specifies a variable name. The attribute value is assigned to the variable |
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Attributes will not interfere with the evaluation of other attributes. So if one attribute sets <<.attr currentTiddler>>, and another attribute uses <<.attr currentTiddler>> in its evaluation, it will use the value of <<.attr currentTiddler>> that exists outside the widget's scope.
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! Examples
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Consider a case where you need to set multiple variables.
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Using the <<.wid vars>> widget, this situation may be handled in the following way:
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```
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\define helloworld() Hello world!
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<$vars greeting="Hi" me={{!!title}} sentence=<<helloworld>>>
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<<greeting>>! I am <<me>> and I say: <<sentence>>
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</$vars>
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```
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In contrast, here is the same example using the <<.wid set>> widget:
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```
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<$set name="greeting" value="Hi" >
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<$set name="me" value={{!!title}} >
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<$set name="sentence" value=<<helloworld>> >
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<<greeting>>! I am <<me>> and I say: <<sentence>>
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</$set>
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</$set>
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</$set>
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```
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! Remarks
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It should be noted that this widget differs from the <<.wid set>> widget in the following ways:
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* A fallback (also known as "emptyValue") cannot be specified
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* Filters cannot be used to produce a conditional variable assignement
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* Variable names must be literal strings
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