[TW5] Clarification of lists with current tiddler

[TonyM]

Folks,

Perhaps this answer is already in my mind but I wish to state it succinctly and see if a more experienced TiddlyWiki Fan can state a simple answer. Question contained within the examples

Case 1. Standard behaviour and use

<$list filter="a filter">

Allows {{!!fieldname}} references including {{!!title}} and <<currentTiddler>> changes with each title in the <$list

Can no longer access the Calling Tiddlers values with {{!!fieldname}} references including {{!!title}}

</$list>

Case 2. Retain access to the calling tiddler 

<$list filter="a filter" variable=mytitle>

Allows {{!!fieldname}} references including {{!!title}} and <<currentTiddler>> will not change, ie uses the tiddlers values where the list is called.

Refer to title as <<mytitle>>

</$list>

Note:

In the above two cases the field references of the form {{!!fieldname}} change from the calling to the listed tiddler

Question

In the cases above what is the best way to access the values of the calling or listed tiddlers fields?

Case 1. Reference the fields of tiddler who's title is available in the calling tiddler

Case 2. Reference the fields of tiddler who's title is available in the <<mytitle>>

Of course an added complication is when you want to use the title or field name and value in widgets, filters, variables within these <$lists we need to use alternate ways to reference said field values. Thus it It gets awfully complex quickly and it is taking a lot of time for me to deeply learn this.

What do I need to know so I do not have to research how every time to use the correct reference method?

Here is a method I use that others may want to know.

My Special use case of a variable I do not use for logical (display or dont display contents)

<$list filter="a filter" variable=null>

Allows {{!!fieldname}} references including {{!!title}} and <<currentTiddler>> will not change, ie uses the tiddlers values where the <$list is called.

Useful for cases where the filter is simply a test as to determine if the content is displayed, 

Tend not to use <<null>>

Can add to the filter limit[1] if the filter can result in more than one value.

</$list>

You can nest multiple lists all with the variable null

A Common filter seems to be "[is[current]<fieldname>] -[[no]]" to display if fieldname has a value of "yes"

Thanks in advance

Tony

[Jed Carty]

I don't think there is a 'best way'. There isn't any convenient shorthand for {{!!fieldname}} for anything other than the tiddler listed in currentTiddler. If you have to reference both the containing tiddler and the current tiddler in the list a lot than you can make a macro like this

\define containingTiddler(field) {{$(containingTiddler)$!!$field$}}

and then in you could do this (example for tiddlywiki.com):

<$set name=containingTiddler value=<<currentTiddler>>>
<$list filter='[tag[HelloThere]]'>
<<containingTiddler title>> - {{!!title}}<br>
</$list>
</$set>

so inside the $list you use <<containingTiddler fieldname>> instead of {{!!fieldname}} when you want the containing tiddler.

It is far from perfect because you have to make the set widget outside the loop each time (or once in the tiddler, it could contain everything else in the tiddler). If you put the macro in a tiddler tagged with $:/tags/Macro you can have that define once for your whole wiki.

[BJ]

may be we could have a 'pop' widget

http://bjhacks.tiddlyspot.com/#pop%20example

[TonyM]

Thanks Jed,

You have done two things for me, provided a resonable solution and confirmed I was not imagining things.

With respect to all the greatness of tiddlywiki this is to me a gap that must be filled, because I for one, and I suspect many others, expected a more direct approach to exist, so its absence was screwing with my mind, it took months for me to be able to even ask this simple question and in the mean time I have run down many rabit holes for many hours not to mention, once desperate, posting in the forum wondering why the solutions were never strait forward.

Unfortunatly intelegent people expect or assume that such simple requirements can already be satisfied in a consistent and comprehencive way in any sophisticated tool.

I am comming to expect I will find a few more as my expertise grows but such gaps really make the learning curve much steeper. I expect this issue alone complicates a lot of user coding, but is also forcing solutions to be convoluted. It is insidious because it is almost imposible to craft search keywords for something that is missing.

I would like to be corrected if I am wrong about this but I would prefer it to be fixed.

Thank you and
Regards
Tony

[Jed Carty]

It may be possible to add something like this to the core, but it wouldn't be straight forward. The biggest problem is determining where the outer containing tiddler is, like if you have multiple lists inside each other how do you determine which containing tiddler you want? It would have to be an nth parent sort of thing and I am not certain that would be any simpler to use than what we have now.

[TonyM]

Jed,

It is true that accessing the nth tiddlers info your be tricky, but just being able to access the 0th would be enough to make big changes. By this I am referring to the tiddler in the face of the user. The logical place they are at, the item listed in the story. This makes me think perhaps we can come at it from another approach.

Personally, It is not if it is core or not, just that a strait forward system exists to reference all fields in the 0th, N-1 and N

If I understand BJ's suggestion its like the push and pop idea where the list pushes items onto a list and pop steps back one item on the list. Using stack metaphors.

As far as I can see although this may very well be helpful, the key references will usually be the 0th, the Nth and the N-1th if you wish to start referencing this such as N-2th or 5th etc... in another iteration, to make the code understandable, then it is more reasonable to start using additional variables etc...

Taking BJ's idea to push and pop his example pops to one layer before and that happens to be the 0th layer. This is a great example of the N-1th, note all we need is a way to reference the 0th without popping (imagine we are 3-4 deep)

So on further consideration what if; as Jed said we had a "convenient shorthand"

An enhancement to the <$list widget perhaps using a parameter, would allow us to request a push (of the references) of the containing tiddler to a stack, and then where ever you are in the nested lists you can either reference 0th or N-1th field values and/or use pop (one or more or N times). In reality a push need only be the storage of containing tiddler-title, if subsequently we have a way of referencing the fields and values from anywhere of that tiddlername. Basically the :N is replaced with the appropriate tiddler title.

As an example (not literal) {{:-1!!fieldname}}  {{:-N!!fieldname}}  {{:0!!fieldname:0}} including [[:N!!fieldname]] [[pretty|:N!!fieldname]] [[pretty|:0!!fieldname]] especially  [[pretty|:0!!title]]

Of course we could perhaps call these "relative tiddler names".

Alternatively we  store the tiddlersname by name eg <$list push="parent" make the tiddlertitle calling this list be stored as parent. Then you can reference {{:parent!!fieldname}}

Perhaps some of Mario's uni-link tech could effectively provide dynamic relative aliases.

Regards

Tony

[Jed Carty]

I believe that we are counting in opposite directions. In the way I was counting the 0th parent would be the current tiddler.

The biggest problem I can see with what you are suggesting where the 0th parent is the outermost tiddler is that the numbering changes when you transclude a tiddler. If you don't have your indexing based on the layer where the calling happens than I think it would be very delicate because you couldn't display the tiddler anywhere else without changing the numbering.

[BJ]

The idea is that pop gets back to the previous value and can be nested:

<$vars currentTiddler=1>
<$vars currentTiddler=2>
<$vars currentTiddler=3>
currentTiddler is <<currentTiddler>><br>

<$pop><$pop>
currentTiddler is <<currentTiddler>><br>
</$pop></$pop>

</$vars>
</$vars>
</$vars>

outputs:

currentTiddler is 3
currentTiddler is 1

The advantage here is that there is no change to any tw syntax, so no backwards compatibility issues.

BJ

[Jed Carty]

BJ,

That looks really good. I think that is the way to go.

TonyM,

Using the pop widget you could make macros like this:

\define parent1(field) <$pop>{{!!$field$}}</$pop>

\define parent2(field) <$pop><$pop>{{!!$field$}}</$pop></$pop>

and so on to go up through the ancestor tiddlers similarly to how you are suggesting.

[PMario]

On Sunday, April 22, 2018 at 4:29:41 AM UTC+2, TonyM wrote:

My Special use case of a variable I do not use for logical (display or dont display contents)

 

A Common filter seems to be "[is[current]<fieldname>] -[[no]]" to display if fieldname has a value of "yes"

IMO the right way to decide if you want to show something using the list widget is

Using tag=script

<$list filter="[all[current]tag[script]]">
...  your content comes here
</$list>

if a tiddler has the non empty field named: hugo

<$list filter="[all[current]has[hugo]]">
show me
</$list>

if a tiddler contains a field hugo, that contains the value "a"

<$list filter="[all[current]hugo[a]]">
show me
</$list>

[TonyM]

Mario,

Thanks, that is a lot cleaner but am I the only one who finds "all current" a bit non intuitive ?

Thanks
Tony