Problem with var in macro

[Jorge Benítez López]

Hello,

I am new in this group. First of all, congratulations and thanks for the work in Tiddlywiki

I have a problem with var in Macro. The first example work but the second no. ¿why?:

1 example:

\define countTag(tag:picture)

$tag$  <$list filter="[tag[$tag$]count[0]]"/>

\end

<<countTag>>

Result:  picture 2

2 example:

\define countTag2()

<<tag2>>: <$list filter="[tag[<<tag2>>]count[0]]"/>

\end

<$set name=tag2 value=picture>

<<countTag2>>

</$set>

Result:  picture 0

I have 2 tiddlys with the tag picture. Why the result is different????

Thanks

[Eric Shulman]

On Thursday, June 17, 2021 at 5:45:48 AM UTC-7 jorgeben...@gmail.com wrote:

\define countTag2()

<<tag2>>: <$list filter="[tag[<<tag2>>]count[0]]"/>

\end

<$set name=tag2 value=picture>

<<countTag2>>

</$set>

Result:  picture 0

I have 2 tiddlys with the tag picture. Why the result is different????

The difference is that when specifying a filter operand, you use square brackets only with literal operand values. Thus, in the first macro, because the $tag$ is a macro parameter that is automatically substituted into the filter syntax by the TWCore macro processor, you  correctly wrote tag[$tag$].  However, in the second macro, tag2 is a variable that is referenced by the tag filter and, when using a variable as the operand of a filter operator, you use single angle brackets to surround a variable operand reference, instead of the square brackets you used previously for the literal $tag$ operand value.  Thus, you need to use: tag<tag2> in your filter syntax.

Your second macro should be written as:

\define countTag2()

<<tag2>>: <$list filter="[tag<tag2>count[0]]"/>

\end

enjoy,

-e

[TW Tones]

This may also be a good opportunity to point out in macros you can also access the content of a variable defined outside the macro, as a substitution using the form $(varname)$ eg $(tag2)$

Tones