Hi Eric
Many thanks for the explanation.
Now, I create a global macro:
\define tagged()
<$set name="target" filter="[<storyTiddler>get[draft.of]]
[<storyTiddler>!has[draft.of]]">
<$list filter="[<target>tagging[]]"/>
</$set>
\end
And there is no output when called :-(
<<tagged>>
Why, in this case, is the macro code not wikified?
regards
On Sunday, 1 November 2015 09:25:57 UTC+2, Eric Shulman wrote:
>
> On Saturday, October 31, 2015 at 9:45:40 PM UTC-7, Matabele wrote:
>>
>> I tried this -- it doesn't work :-(
>> I created a global macro:
>> \define currentTitle()
>> <$list filter="[<storyTiddler>get[draft.of]]
>> [<storyTiddler>!has[draft.of]]">
>>
>> </$list>
>> \end
>>
>> The result of a simple macrocall is as expected in both view and edit
>> mode:
>> <<currentTitle>>
>>
>> However, when I try this, there is no output in either view or edit mode:
>>
>> <$list filter="[tag<currentTitle>]"/>
>> <$list filter="[<currentTitle>tagging[]]"/>
>> <$list filter="[<currentTitle>listed[tags]]"/>
>>
>> Anyone know why?
>>
>
> There is a widespread and common misperception about macros.
> Specifically, because they have a parameter passing syntax, they *look*
> somewhat like the function syntax in other languages. As a result, there
> is an expectation that they *work* like functions do, and can "compute and
> return" a resulting value. However.... macros don't actually do any
> computation other than simple *text substitution* to replace any instances
> of $paramname$ and $(variablename)$ within the macro content and then
> return that modified content for further handling.
>
> What happens with that result depends on where it is used:
>
> * If the macro result is returned directly into a wiki context (i.e.
> <<macroname ...>> is embedded directly in wikitext), then the macro's
> output will be parsed ("wikified") and any <$widgets> and/or <<macroname>>
> references are then processed in turn.
> * If a macro result is used as a widget parameter (e.g., <$widget
> paramname=<<macroname>>...></$widget>) or as a reference within a filter
> (e.g., [tag<macroname>]), then the macro's output is *not* parsed, and is
> simply used as literal text by the widget or filter handler.
>
> The confusion arises because of this different contextual handling for the
> macro results...
>
> In your example, the output of the "currentTitle" macro, which has no
> parameters, is always, literally:
> <$list filter="[<storyTiddler>get[draft.of]] [<storyTiddler>
> !has[draft.of]]">
>
> </$list>
>
> In the first context, where you parse and render the output of
> <<currentTitle>>, the <$list> widget is invoked, and the expected output is
> shown. However, in the second context, where you use
> [...<currentTitle>...] within a filter, the output of the macro is *not*
> parsed, so the filter is, literally:
> <$list filter="[tag[<$list filter="[<storyTiddler>get[draft.of]]
> [<storyTiddler>!has[draft.of]]">
>
> </$list>]]"/>
>
> One possible work-around is to first use the <$set> widget with the
> filter="..." param to get the actual filter result (the desired tag name),
> and then use that variable within the subsequent list filter (to list
> tiddlers that are tagged with that name), like this:
> <$set name="target" filter="[<storyTiddler>get[draft.of]] [<storyTiddler>
> !has[draft.of]]">
> <$list filter="[tag<target>]"/>
> </$set>
>
> I hope this explanation helps,
>
> enjoy,
> -e
>
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