On Sunday, February 28, 2016 at 10:18:37 AM UTC-8, Mat wrote:
>
> It just seem so fundamental and it has popped up before... but I can't
> find any solution:
>
Your confusion stems from the fact that, despite the ability to have
parameters, macros are not "functions" in the usual sense.
Macros don't "run" their content and "return the output". A macro is
simply a text substitution mechanism, and the ONLY action it performs is to
replace any embedded parameters and/or variables -- the $param$ and
$(variable)$ syntax -- and then return the modified content for further
handling by the calling context. Other than this replacement processing,
macros *never* "evaluate" (aka, "wikify") their output; that is *always*
the responsibility of the context in which the macro is invoked.
The stored result (regardless if using a direct macro call or via the set
> variable) gives the result to be a copy of the literal macro string rather
> than the *evaluated *macro result.
>
> \define c() <$count filter="[prefix[New]]"/>
>
> <$set name="c2" value=<<c>>>
> <$button>
> <$action-setfield result=<<c>> result2=<<c2>>/>
> x
> </$button>
> </$set>
>
> What can be done? Couldn't there be some generic macro parameter to state
> if the return value should be the evaluated result?
>
As noted above, the "evaluation" of the macro results depends entirely on
the context into which it is returned: the macro content *might* be
rendered (and thus, "wikified"), or it might be used as the value of a
widget parameter, or perhaps saved as-is to a tiddler field, etc.
The immediate problem here is that you are trying to use the $count widget
to get a value that you want to store in a variable. This won't work,
because the $count widgets job is to simply display the total number of
items in the filter result. Thus, while it produces rendered output, it
doesn't actually "return" a value that can be stored.
What you really need is a [count[]] *filter*... then, you could use the
$set widget to store the results of the filter.
Here's the code for a simple "count" filter:
/*\
title: filters/count.js
type: application/javascript
module-type: filteroperator
author: EricShulman
description: Filter operator for getting the number of items in a list
\*/
(function(){
/*jslint node: true, browser: true */
/*global $tw: false */
"use strict";
exports.count = function(source,operator,options)
{ var c=0; source(function(tiddler,title) { c++; }); return [c.toString
()]; };
})();
Put the above code into the text field of a tiddler, and set fields
type="application/javascript"
and
module-type="filteroperator"
Then save-and-reload for the new filter to be available.
Here's how you would use it:
<$set name="c" filter="[prefix[New]count[]]"
<$button> X
<$action-setfield result=<<c>>/>
</$button>
</$set>
enjoy,
-e
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