On Saturday, November 20, 2021 at 12:12:54 PM UTC+1 CarloGgi wrote:
> Hi PMario, thanks a lot, indeed my code is inconsistent because in an
> attempt to give a generic example, not tied tho the specific issue, I tried
> to simplify it (and I ended up to over-simplify it).
>
I thought about this, that's why I did try to create something that could
have been a possibility and shows how TW filters work. .. Filters are the
powerful thing in TW.
If you come from a programmers background, TW is different and needs a bit
of a different thinking, because it is targeted to non-programmers ...
The whole TW UI is built with filters and wikitext templates and makes
heavy use of recursions especially in the core code.
> Lots of stuff to reply to, let's go through it point by point:
>
> 1. indeed widgets are no programming language, that's why I used the word
> 'environment', not 'language';
>
Widgets don't have a return value ... They manipulate the DOM ... eg:
```
<ul>
<$list filter="[tag[todo]]">
<li><$text text=<<currentTiddler>> /></li>
</$list>
</ul>
```
>From a programmers point of view, you'd probably want to "add" some
variables inside the "list -loop"... But
Let's say I have 2 tiddlers "a" and "b" tagged "todo"
`[tag[todo]]` returns a list and the list widget internally assigned the
element to an internal variable named `currentTiddler`, then it iterates
over the list and outputs the dom elements in the "list-body".
The "list-body" is between `<$list filter ...> list body is here
</$list>` which looks similar to a function, but it isn't...
The resulting HTML code will look like this:
```
<ul>
<li>a</li>
<li>b</li>
</ul>
```
So widgets don't calculate variables, they are used to manipulate the HTML
output ....
```
<ul>
<$list filter="[tag[todo]]">
<li><$link /></li>
</$list>
</ul>
```
This example uses a lot of shortcuts with TW default values. `<$list
filter="[tag[todo]]">` is a shortcut for: `<$list filter="[tag[todo]]"
variable="currentTiddler" >`. `<$link />` is a shortcut for `<$link
to=<<currentTiddler>> />`
The HTML output is
```
<ul>
<li><a class="tc-tiddlylink tc-tiddlylink-resolves" href="#a">a</a></li>
<li><a class="tc-tiddlylink tc-tiddlylink-resolves" href="#b">b</a></li>
</ul>
```
> 2. .... it is frustratingly difficult to output a number of text entries
> (filtered out from a db made of data tiddlers) excluding duplicates, and
> this because in TW you cannot assign to a 'variable' other than at
> declaration time, so you cannot incrementally append your entries to a
> 'list' variable for post-processing.
>
That's right from a programmers point of view. ... But it will be very
elegant, once you understand the mechanism. ...
As I wrote TW uses sensible defaults for widget parameters, that's why it
is important to have a closer look at the docs. ..
> Acknowledging that TW is not a full-featured programming language, I'm
> pretty much sure that it was conceived to enable users to do such kind of
> stuff: filter out and manipulate chunks of text;
>
As I wrote it's built to manipulate text. .. As above it's designed to
manipulate the DOM ... May be this view will make it clearer for you.
> 3. filters have if-then-else logic but only to a limited scope. Filters'
> if-then-else statements can only output text strings;
>
Not really, they can also be used with variables eg:
`[tag[todo]get<variable>]` or `[tag[todo]get{reference}]`
With the *first* example if you $set variable to eg: `hugo`, it will read
the content of the `hugo` field.
The *second* example will use the 'text' field of the tiddler 'reference',
reads the content of that field and uses this value to read the value of
the "todo" tiddler. ... So it's similar to a "pointer".
> 4. filters indeed create and deal with lists, so the only place where
> hopefully I can do my processing is within a filter, but it is quite
> difficult to write a one-liner that does what I want,
>
Yes, filters can become complex. So sometimes it is needed to define
several variables upfront, that contain "filtered" elements already. ...
It's also a bit of the speed advantage, because wikitext is "interpreted",
but heavily cached. ...
> let me paste my true code below (I'm sure that a better developer could
> write a more elegant, more synthetic one merging some of the <$list>
> widgets together into a single one)...
>
>
I'll have a closer look at the code and write a new post ...
--
You received this message because you are subscribed to the Google Groups
"TiddlyWiki" group.
To unsubscribe from this group and stop receiving emails from it, send an email
to tiddlywiki+unsubscr...@googlegroups.com.
To view this discussion on the web visit
https://groups.google.com/d/msgid/tiddlywiki/2d4f367f-38fb-4f82-836f-6352f8a3ad16n%40googlegroups.com.
