111 lines
3.4 KiB
Plaintext
111 lines
3.4 KiB
Plaintext
created: 20230421020225031
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modified: 20230726145912019
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tags:
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title: Variable Usage
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type: text/vnd.tiddlywiki
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!Ways to define variables and parameters
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|! how declared|! how parameters are defined|! accessing parameter values in the body|
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|\define|`()`|`$param$, <<__param__>>`|
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|~|<<.wlink ParametersWidget>> or `\parameters`|`<<param>>`|
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|<<.wlink SetWidget>>, <<.wlink LetWidget>>, <<.wlink VarsWidget>>|<<.wlink ParametersWidget>> or `\parameters`|`<<param>>`|
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|\procedure, \widget|`()`, <<.wlink ParametersWidget>> or `\parameters`|`<<param>>`|
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|\function|`()`|`<param>`|
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|javascript macros|`exports.params` javascript property array|passed as normal javascript function parameter and so accessed as a normal javascript variable|
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!!Examples
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These examples are meant to provide insight into the various ways of defining and using parameters. In many cases they do not illustrate best practices.
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!!! \define
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<$let eg='\define mp1(a1) $a1$ - <<__a1__>>
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\define mp2() <$parameters a1><<a1>></$parameters>
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\define mp3()
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\parameters(a1)
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<<a1>>
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\end
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|<<mp1 foo>>|<<mp2 foo>>|<<mp3 foo>>|
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'>
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<$macrocall $name="copy-to-clipboard-above-right" src=<<eg>>/>
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<$codeblock code=<<eg>>/>
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</$let>
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!!! $set, $let, $vars
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<$let eg='<$set name="sp1" value="<$parameters a1><<a1>></$parameters>">
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<$set name="sp2" value="""
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\parameters(a1)
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<$parameters a1><<a1>></$parameters>
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""">
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<$vars vp1="<$parameters a1><<a1>></$parameters>" vp2="""
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\parameters(a1)
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<$parameters a1><<a1>></$parameters>
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""">
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<$let lp1="<$parameters a1><<a1>></$parameters>" lp2="""
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\parameters(a1)
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<$parameters a1><<a1>></$parameters>
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""">
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|<<sp1 foo>>|<<sp2 foo>>|
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|<<vp1 foo>>|<<vp2 foo>>|
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|<<lp1 foo>>|<<lp2 foo>>|
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</$let>
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</$vars>
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</$set>
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</$set>
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'>
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<$macrocall $name="copy-to-clipboard-above-right" src=<<eg>>/>
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<$codeblock code=<<eg>>/>
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</$let>
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!!! \procedure, \widget
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<$let eg='\procedure pp1(a1) <<a1>>
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\procedure pp2() <$parameters a1><<a1>></$parameters>
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\procedure pp3()
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\parameters(a1)
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<<a1>>
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\end
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\procedure wp1(a1) <<a1>>
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\widget wp2() <$parameters a1><<a1>></$parameters>
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\widget wp3()
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\parameters(a1)
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<<a1>>
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\end
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|<<pp1 foo>>|<<pp2 foo>>|<<pp3 foo>>|
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|<<wp1 foo>>|<<wp2 foo>>|<<wp3 foo>>|
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'>
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<$macrocall $name="copy-to-clipboard-above-right" src=<<eg>>/>
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<$codeblock code=<<eg>>/>
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</$let>
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!!! \function
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<$let eg='\function fp1(a1) [<a1>]
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|<<fp1 foo>>|'>
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<$macrocall $name="copy-to-clipboard-above-right" src=<<eg>>/>
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<$codeblock code=<<eg>>/>
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</$let>
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!Behaviour of invoked variables depends on how the variable was declared
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{{Behaviour of invoked variables depends on how the variable was declared}}
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!Namespaces
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*''tiddler titles'' - tiddlers are uniquely identified by their title. The namespace for tiddler titles and variable names are completely separate.
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*''variables'' - \define, <<.wlink SetWidget>>, <<.wlink LetWidget>>, <<.wlink VarsWidget>>, \procedure, \widget, \function all create variables. If the same name is used, then later define will overwrite earlier defined
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*''<<.op function>> filter operator parameter'' - only variables defined using \function can be called using the <<.olink function>> operator
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*''filter operators'' - only the [[javascript defined filter operators|Filter Operators]] and variables defined using \function with name containing a dot can be called
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*''widgets'' - variables defined using \widget can be invoked using `<$widget/>` syntax ONLY if the name starts a dollar sign. Without the dollar sign prefix, defining variables using \widget is no different than using \procedure.
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