Position in list code pattern? Challenge

[TonyM]

Folks,

I have an interesting idea, that requires the ability to get the position of a tiddlers title in a list field and return it as a number.

So if we consider the tag $:/tags/ViewTemplate then on tiddlywiki.com the Tiddler $:/core/ui/ViewTemplate/subtitle would return three (3)

I have a code pattern to achieve this using count, setWidget with its index parameter, and a range operator however it is quite long winded and possibly inefficient.

Is anyone aware of an efficient way to determine the position of a given tiddler name in a list ?

I will share the idea once get past this, in a separate thread. However I need to determine the position in a list many times over so an efficient method is critical.

Thanks in Advance

Tony 

[Eric Shulman]

On Monday, January 13, 2020 at 3:30:36 PM UTC-8, TonyM wrote:

Is anyone aware of an efficient way to determine the position of a given tiddler name in a list ?

How about something like this:

<$list filter="NOMATCH A B C D E +[allbefore<target>count[]] " />

Notes:

* <target> is the title you are looking for

* if target doesn't exist in the list, the result is "0"

* NOMATCH is used as a "sentinel" value so that valid matches start with "1"

Thus, if in the above example

   target="FOO" returns 0

and

   target="A" returns 1

   target="B" returns 2

   etc.

let me know how it goes...

enjoy,

-e

[TonyM]

Eric,

beautiful work. Love it. Nice and minimal. Thanks.

I will now look to using this to get a compound number 1.2.4 from a toc structure.

My design idea was to autogenerate a position in list or toc number and display it before or after the tiddler title
eg; "chapter title" n
or 1.2.3.4 tiddler title in toc

This is for tiddlers not toc lists but the numbers should match those in a numbered toc.

Thanks again
Tony

[TonyM]

Folks,

I notice here, the list field only comes into existence if one drags and drops a tiddler in the tag pill popup.

Is any one aware of a programmatic way to cause this to happen?

Regards

Tony

[TonyM]

Folks,

Using Erics Tips;

here is an example of finding the current tiddlers position in a list of the give tag "Code Patterns"

<$list filter="[[NOMATCH]] [enlist{Code Patterns!!list}] +[allbefore<currentTiddler>count[]]" />

Regards

Tony

On Tuesday, January 14, 2020 at 10:30:36 AM UTC+11, TonyM wrote:

[Mohammad]

I think if it uses allbefore:include then there is no need for NOMATCH!

like below

<$list filter="A B C D E +[allbefore:include<target>count[]] " />

--Mohammad

[Mohammad]

For email reader: The post edited.

[TonyM]

Mohammad,

Thanks, I note you example has a trailing space inside the filter.

All,

I have submitted a variation as an example to the documentation on tiddlywiki.com

A B C D E +[allbefore:include[C]count[]]

Regards

Tony

[TonyM]

Bump 

Any idea on this one?

Folks,

I notice here, the list field only comes into existence if one drags and drops a tiddler in the tag pill popup.

Is any one aware of a programmatic way to cause this to happen, the creation of the list field?

Regards

Tony