24 lines
1.7 KiB
Plaintext
24 lines
1.7 KiB
Plaintext
created: 20141002133113496
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modified: 20221221175615776
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tags: Concepts Reference
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title: Variables
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type: text/vnd.tiddlywiki
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A <<.def variable>> is a snippet of text that can be accessed by name within a particular branch of the [[widget tree|Widgets]]. The snippet is known as the variable's <<.def value>>.
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A new variable is defined using a <<.wlink SetWidget>> or <<.wlink LetWidget>> widget, and is then available to any of the children of that widget, including transcluded content. A <<.wid set>> widget can reuse an existing name, thus binding a different snippet to that name for the duration of the widget's children.
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The <<.wlink ListWidget>> widget by default sets a particular variable <<.var currentTiddler>> to each listed title in turn.
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For an overview of how to use variables, see [[Variables in WikiText]].
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Despite the term <<.word variable>>, ''each snippet is a constant string''. The apparent variability is actually the result of the presence of multiple variables with the same name in different parts of the widget tree.
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[[Macros]] are a special form of variable whose value can contain placeholders that get filled in with parameters whenever the macro is used.
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By themselves, the snippets are <<.em not>> parsed as WikiText. However, a variable reference will transclude a snippet into a context where ~WikiText parsing <<.em may>> be occurring. Within a snippet, the only markup detected is `$name$` for a macro parameter transclusion and `$(name)$` for a variable transclusion.
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The <<.mlink dumpvariables>> macro lists all variables (including macros) that are available at that position in the widget tree.
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~TiddlyWiki's core has [[several variables|Core Variables]] built in.
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