29 lines
1.1 KiB
Plaintext
29 lines
1.1 KiB
Plaintext
created: 20221009124003601
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modified: 20230419103154328
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tags: Concepts Reference
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title: Functions
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type: text/vnd.tiddlywiki
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!! Introduction
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<<.from-version "5.3.0">> A <<.def function>> is a named snippet of text containing a [[Filter Expression]]. Functions can have named parameters which are available within the function as variables.
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Functions are usually defined with the [[Pragma: \function]]:
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```
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\function my-function(parameter:"2")
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[<parameter>multiply[1.5]]
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\end
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```
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Functions can be invoked in several ways:
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* Directly transclude functions with the syntax `<<myfn param:"value">>`
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* Assign functions to widget attributes with the syntax `<div class=<<myfn param:"value">>>`
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* Invoke functions via the [[function Operator]] with the syntax `[function[myfn],[value],...]`
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* Directly invoke functions whose names start with a period as custom filter operators with the syntax `[.myfn[value]]`
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!! How Functions Work
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Functions are implemented as a special kind of [[variable|Variables]]. The only thing that distinguishes them from ordinary variables is the way that the parameters are handled.
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