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TiddlyWiki5/editions/tw5.com/tiddlers/wikitext/Conditional Shortcut Syntax.tid
Jeremy Ruston b7562f0c7b
Conditional Shortcut Syntax (#7710)
* Initial Commit

* Update docs

* Add support for elseif blocks

* Another test

* WIP

* Change from `{%if%}` to `<%if%>`

See discussion here - https://talk.tiddlywiki.org/t/proposed-if-widget/7882/64

* Don't use the widget body as the template if a list-empty widget is present

See discussion here - https://github.com/Jermolene/TiddlyWiki5/pull/7710#issuecomment-1717193296

* List widget should search recursively for list-template and list-empty

* Allow block mode content within an if/then/else clause

* Update docs

* Add from-version tag to docs
2023-10-14 09:41:21 +01:00

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created: 20230901122740573
modified: 20230901123102263
tags: WikiText
title: Conditional Shortcut Syntax
type: text/vnd.tiddlywiki
<<.from-version "5.3.2">> The conditional shortcut syntax provides a convenient way to express if-then-else logic within WikiText. It evaluates a filter and considers the condition to be true if there is at least one result (regardless of the value of that result).
A simple example:
<$macrocall $name='wikitext-example-without-html'
src='<% if [{$:/$:/info/url/protocol}match[file:]] %>
Loaded from a file URI
<% else %>
Not loaded from a file URI
<% endif %>
'/>
One or more `<% elseif %>` clauses may be included before the `<% else %>` clause:
<$macrocall $name='wikitext-example-without-html'
src='<% if [{$:/$:/info/url/protocol}match[file:]] %>
Loaded from a file URI
<% elseif [{$:/$:/info/url/protocol}match[https:]] %>
Loaded from an HTTPS URI
<% elseif [{$:/$:/info/url/protocol}match[http:]] %>
Loaded from an HTTP URI
<% else %>
Loaded from an unknown protocol
<% endif %>
'/>
The conditional shortcut syntax can be nested:
<$macrocall $name='wikitext-example-without-html'
src='\procedure test(animal)
<% if [<animal>match[Elephant]] %>
It is an elephant
<% else %>
<% if [<animal>match[Giraffe]] %>
It is a giraffe
<% else %>
It is completely unknown
<% endif %>
<% endif %>
\end
<<test "Giraffe">>
<<test "Elephant">>
<<test "Antelope">>
'/>
Notes:
* Clauses are parsed in inline mode by default. Force block mode parsing by following the opening `<% if %>`, `<% elseif %>` or `<% else %>` with two line breaks
* Within an "if" or "elseif" clause, the variable `condition` contains the value of the first result of evaluating the filter condition
* Widgets and HTML elements must be within a single conditional clause; it is not possible to start an element in one conditional clause and end it in another
* The conditional shortcut syntax cannot contain pragmas such as procedure definitions